samples FKM-1 to FKM-100

 

!! THIS PAGE IS NO LONGER MENU-ACCESSIBLE AND HAS NOT BEEN UPDATED RECENTLY. YOU PROBABLY ARRIVED HERE FROM AN OLD BOOKMARK OR AN OUT-OF-DATE SEARCH-ENGINE LINK. PLEASE SELECT A PAGE FROM THE “THIN SECTION SCANS” TAB ABOVE FOR THE CURRENT VERSION OF THIS PAGE… THANK YOU. !!

 



Merelani Tanzania tsavorite in thin section

sample: FKM-1
locality: Merelani Hills, Lelatema Mtns., Simanjiro district, Manyara region, Tanzania.
rock type: grossular-zoisite “skarn”. Granulite facies calc-silicate with retrograde amphibolite facies overprinting; possibly a meta-marl, with accompanying metasomatism. Specimens such as this with coarse grossular (and those with coarse tanzanite… see sample FKM-13, also from Merelani) are reported to occur in locally “low pressure” pockets and veins.
major mineralogy: Vanadium-bearing grossular garnet (“tsavorite”; with higher V in patches and rims) associated with zoisite+quartz+calcite symplectite, with minor additional calcite, diopside, graphite, sulfides, and titanite (up to 0.4 wt% V, so considerably less V-enriched than titanite in sample FKM-26, also from Merelani). Sparse scattered apatite is also present.
photomicrographs of FKM-1
(unpolarized light)

mineral representative mineral compositions in FKM-1
pyrrhotite (Fe0.90Ni0.01)S1.00
pyrite Fe1.00S2.00
fluorapatite (Ca5.03Y0.01)[P2.94Si0.04O12](F0.87[OH]0.12)
grossular (most Mn-rich) (Ca2.65Mn2+0.31Mg0.01)(Al2.00V0.01Fe3+0.01Mn3+0.01)[Si2.95Al0.040.01O11.96F0.04]
grossular (most V-rich) (Ca2.91Mg0.05Mn2+0.04)(Al1.85V0.10Ti0.02Cr0.01Mn3+0.01)[Si2.97Al0.020.01O11.96F0.04]
titanite Ca1.00(Ti0.75Al0.24V0.01)(O0.75F0.15[OH]0.10)[Si0.99Al0.01O4]
zoisite Ca1.00Ca1.00Al1.00Al1.00Al1.00O[Si2.00O7][Si1.00O4](OH)
diopside Ca1.00Mg1.00[Si2.00O6]

Merelani Tanzania tsavorite in thin section

same as previous FKM-1 image (under crossed polars).

 




St. Marcel Italy piemontite in thin section

sample: FKM-2
locality: Prabornaz mine, Saint-Marcel, Val d’Acosta, Italy.
rock type: titanite-piemontite schist. Greenschist to amphibolite facies meta-Mn-rich sediment (distal volcanogenic exhalite?), with superimposed metasomatism.
major mineralogy: Strikingly pleochroic Sr-rich piemontite with Sb-rich titanite, with minor quartz and orthoclase. Minor braunite and sparse rutile are also present. Sample FKM-171 is also from the Prabornaz mine, but represents a different assemblage (mica-bearing and more rich in Mn-oxides).
photomicrographs of FKM-2
(unpolarized light)

mineral representative mineral compositions in FKM-2
rutile (Ti0.98Mn4+?0.01Fe3+0.01)O2
braunite (Mn2+0.80Ca0.20)(Mn3+5.45Fe3+0.49Al0.02)O8[Si1.02O4]
titanite (most Sb-rich) (Ca1.00Na0.01)(Ti0.78Sb5+0.12Fe3+0.04Mn3+0.03Al0.02)(O0.99[OH]0.01)[Si0.98Al0.02O4]
piemontite (most Sr-rich) (Ca0.97Mn2+0.03)(Ca0.61Sr0.36)(Al0.62Fe3+0.38)Al(Mn3+0.77Fe3+0.18Mn2+0.05)O[Si2.02O7][Si1.01O4](OH)
orthoclase (K0.92Na0.06Ba0.01)[Si2.98Al1.02O8]

St. Marcel Italy piemontite in thin section

same as previous FKM-2 image (under crossed polars).

 




Palos Hill Greece glaucophane and jadeite blueschist in thin section

sample: FKM-3
locality: Palos Hill, Gria Spilia, Syros Island, Cyclades chain, Greece.
rock type: Na-(Ca) clinopyroxene-glaucophane schist. Blueschist facies transitional to (or perhaps retrogressed from) eclogite facies; metavolcanic or meta-volcaniclastic(?)
major mineralogy: Nybøite was reported for this sample, but all of the amphibole examined in this thin section was verified as glaucophane by EPMA. This sample also contains abundant jadeite/omphacite clinopyroxene solid solution and paragonite/phengite dioctahedral mica solid solution. Subordinate epidote (with Sr- and REE-rich growth zones), along with scattered titanite, rutile (also with ~716 ppm Cr) and monazite, are also present.
(unpolarized light)

mineral representative mineral compositions in FKM-3
rutile (Ti0.98Fe3+0.01)O2
monazite-(Ce) (Ce0.44La0.21Nd0.14Y0.05Pr0.04Ca0.03Th0.03Sm0.02Gd0.02[HREE]0.01)[P0.99Si0.01O4]
titanite Ca0.99(Ti0.88Al0.10Fe3+0.02)(O0.89[OH]0.06F0.05)[Si1.00O4]
epidote (most Sr+REE-rich) (Ca0.93Mn2+0.06Na0.01)(Ca0.54Ce0.23La0.09Sr0.07Nd0.02Pr0.01[M+HREE]0.01)Al1.00Al1.00
(Fe2+0.43Fe3+0.34Al0.20Sc0.01Mg0.01Ti0.01)(O0.97F0.03)[Si2.02O7][Si1.01O4](OH)
epidote (bulk) (Ca0.89Mn2+0.08Fe2+0.03)(Ca0.95)Al1.00Al1.00
(Fe3+0.79Fe2+0.09Al0.08Sc0.02Cr0.01)O[Si2.03O7][Si1.01O4](OH)
jadeite-dominant cpx ss (Na0.84Ca0.12Mg0.02)(Al0.52Fe3+0.29Fe2+0.12Mg0.07)[Si2.01O6]
omphacite-dominant cpx ss (Na0.59Ca0.37Mg0.03)(Al0.38Mg0.28Fe3+0.18Fe2+0.15)[Si2.01O6]
aegirine-augite-dominant cpx ss (Na0.71Ca0.24Mg0.02)(Fe3+0.36Al0.30Mg0.19Fe2+0.15)[Si2.02O6]
glaucophane (Na0.04K0.010.95)(Na1.81Ca0.19)(Mg1.89Al1.43Fe2+0.98Fe3+0.62Ti0.01Zn0.01Cr0.01)
[Si7.78Al0.22O22]([OH]1.91F0.07O0.02)
muscovite-dominant dioct mica ss (K0.82Na0.050.12)(Al1.55Mg0.29FeT0.18Ti0.01Cr0.010.95)[Si3.42Al0.58O10]([OH]1.96F0.04)
paragonite-dominant dioct mica ss (Na0.82K0.03Ca0.010.15)(Al1.99FeT0.05Mg0.010.94)[Si3.03Al0.97O10]([OH]1.98F0.02)

Palos Hill Greece glaucophane and jadeite blueschist in thin section

same as previous FKM-3 image (under crossed polars).

 




Kiona Bay Greece glaucophane and epidote blueschist in thin section

sample: FKM-4
locality: Kiona Bay, Tinos, Greece.
rock type: epidote-glaucophane schist. Transitional(?) between greenschist and blueschist facies metavolcanic(?)
major mineralogy: Porphyroblasts of epidote (relict greenschist?), minor garnet, and rare zones of winchite (originally reported to be ferrowinchite), with some actinolite (seemingly retrograde in texture) and muscovite, and abundant glaucophane. Scattered rutile (also with ~602 ppm Cr and ~183 ppm Mn) is also present.
(unpolarized light)

mineral representative mineral compositions in FKM-4
rutile (Ti0.98Fe3+0.01)O2
magnetite Fe2+1.00(Fe3+1.97V0.01Si0.01)O4
fluorapatite Ca5.02[P2.99O12](F0.87[OH]0.13)
almandine (core) (Fe2+1.65Ca0.80Mn2+0.33Mg0.19)(Al1.91Fe3+0.09Ti0.01)[Si2.97Al0.03O12]
almandine (middle) (Fe2+1.79Ca0.78Mg0.22Mn2+0.19)(Al1.96Fe3+0.04Ti0.01)[Si2.98Al0.02O12]
almandine (rim) (Fe2+1.76Ca0.84Mg0.30Mn2+0.09)(Al1.97Fe3+0.03)[Si2.98Al0.01O12]
titanite Ca1.00(Ti0.95Al0.04Fe3+0.01)(O0.94[OH]0.06F0.01)[Si0.99Al0.01O4]
epidote (Ca0.94Fe2+0.05Mn2+0.01)Ca0.97Al1.00Al1.00(Fe3+0.50Al0.41Fe2+0.06Mg0.01V0.01Ti0.01)O[Si2.02O7][Si1.01O4](OH)
omphacite (Ca0.50Na0.47Mg0.03)(Mg0.40Al0.38Fe2+0.14Fe3+0.07)[Si2.00O6]
glaucophane 1.00(Na1.85Ca0.09Fe2+0.05)(Mg2.13Al1.76Fe2+1.05Fe3+0.05Cr0.01)[Si8.01O22](OH)2.00
winchite (Na0.02K0.020.95)(Ca1.29Na0.71)(Mg3.03Fe2+0.78Fe3+0.60Al0.52Mn2+0.04Cr0.02V0.01Ti0.01)
[Si7.51Al0.49O22]([OH]1.95F0.03O0.01)
actinolite (K0.010.99)(Ca1.66Na0.28Mn2+0.03Fe2+0.03)(Mg3.66Fe2+1.06Al0.25Fe3+0.03)[Si7.99Al0.01O22]([OH]1.98F0.02)
muscovite (K0.90Na0.020.07)(Al1.50Mg0.35FeT0.14Ti0.01Cr0.010.99)[Si3.50Al0.50O10](OH)2.00
clinochlore (Mg2.67FeT1.96Al1.21MnT0.040.11)[Si2.81Al1.19O10](OH)8.00

Kiona Bay Greece glaucophane and epidote blueschist in thin section

same as previous FKM-4 image (under crossed polars).

 




Cape Marmari Greece muscovite pseudomorph after lawsonite in thin section

sample: FKM-5
locality: Cape Marmari, Grammata Bay, Syros Island, Cyclades chain, Greece.
rock type: heavily altered or retrogressed blueschist.
major mineralogy: The sample is now nearly entirely muscovite pseudomorphs after lawsonite, along with subordinate calcite and scattered actinolite, clinozoisite, pumpellyite-(Al), titanite and clinochlore. Originally reported to contain chromian lawsonite, but no relict lawsonite remains in this thin section.
(unpolarized light)

mineral representative mineral compositions in FKM-5
titanite Ca1.00Ti1.00O[Si1.00O4]
pumpellyite-(Al) (Ca1.95Fe2+0.02Mn2+0.01Na0.01)(Al0.49Mg0.45FeT0.03Ti0.01V0.01Cr0.01)Al2.00
[Si2.01O7][Si1.00O4]([OH]~1.37O~0.55F0.08) . H2O
clinozoisite (Ca0.97Fe2+0.03)(Ca0.97Sr0.02)Al1.00Al1.00(Al0.73Fe3+0.25Cr0.01Ti0.01)O[Si1.99Al0.01O7][Si1.00O4](OH)
actinolite (Na0.02K0.010.97)(Ca1.64Na0.36)(Mg3.62Fe2+0.90Al0.31Fe3+0.13Ni0.02Cr0.01Mn2+0.01)[Si7.88Al0.12O22]([OH]1.95F0.04)
muscovite (K0.62Na0.32Ca0.02Sr0.010.04)(Al1.84Mg0.07FeT0.06Ti0.04Cr0.010.98)[Si3.03Al0.97O10](OH)2.00
clinochlore Ca0.01(Mg3.43FeT1.20Al1.15Ni0.02MnT0.010.18)[Si2.92Al1.08O10]([OH]7.98F0.02)

Cape Marmari Greece muscovite pseudomorph after lawsonite in thin section

same as previous FKM-5 image (under crossed polars).

 




Ottre Belgium chloritoid schist in thin section

sample: FKM-6
locality: Ottré, Vielsalm, Stavelot massif, Luxembourg Province, Belgium.
rock type: chloritoid phyllite. Greenschist facies (chlorite zone) metapelite.
major mineralogy: Porphyroblasts of chloritoid (originally reported to be ottrélite, but Mn is only ~0.3 apfu, verified by EPMA), with abundant chlorite and muscovite, and tiny widepread hematite. Scattered apatite and monazite are also present.
(unpolarized light)

mineral representative mineral compositions in FKM-6
fluorapatite (Ca4.97Na0.01Nd0.01Y0.01)[P2.97Si0.02O12](F0.75[OH]0.25)
chloritoid (core) (Fe2+1.53Mn2+0.29Mg0.19)Al3.96[Si1.01O4]2(OH)4.00
chloritoid (rim) (Fe2+1.47Mg0.28Mn2+0.27)(Al3.93Fe3+0.02)[Si1.01O4]2(OH)4.00
muscovite (K0.73Na0.05Ba0.010.21)(Al1.57Mg0.23FeT0.23Ti0.030.94)[Si3.42Al0.58O10]([OH]1.90F0.10)
clinochlore Na0.01(Mg2.31FeT1.70Al1.67MnT0.09Zn0.010.22)[Si2.57Al1.43O10]([OH]7.99F0.01)

Ottre Belgium chloritoid schist in thin section

same as previous FKM-6 image (under crossed polars).

 




Eifel Germany nosean phonolite in thin section

sample: FKM-7
locality: Schellkopf, Brenk, Niederzissen, Eifel, Rhineland-Palatinate, Germany.
rock type: nosean phonolite.
major mineralogy: Nosean and sanidine in a fine-grained to glassy felsic volcanic matrix.
(unpolarized light)

Eifel Germany nosean phonolite in thin section

same as previous FKM-7 image (under crossed polars).

 




Franklin New Jersey norbergite marble in thin section

sample: FKM-8
locality: Franklin mining district, Sussex Co., NJ, USA.
rock type: high grade norbergite marble. Granulite facies metamorphosed siliceous dolostone.
major mineralogy: Abundant norbergite, partially altered (seemingly to serpentine ± brucite in the optical image, but not easily identified in BSE imaging), in carbonate (calcite > dolomite; very minor strontianite). Also present are scattered chondrodite (thus two different humite group minerals are present) separated from intergrown fluoro-pargasite by a thin rim of chlorite. Ba-rich phlogopite inclusions are present in the amphibole, and scattered tremolite (as a secondary mineral?) is also present. The norbergite and chondrodite normalizations include estimates of possible B present (0.03 wt% B and 0.16 wt% B, respectively). Although not verified by independent ICP-MS or SIMS analyses, these added low B estimates improve the T-site occupancy, are permissible based on studies of B incorporation into humite group minerals (Gerasimova et al., 2013 [← subscription required]; Woodford, 1995; Hinthorne and Ribbe, 1974), and are consistent with the notable B-enrichments observed in the Franklin area marbles (for example, see sample FKM-37 [with fluoborite] and sample FKM-184 [with warwickite]). Additional analytical notes: OH replacing O is calculated as equal to B apfu, according to the exchange vector [B(OH)]1[SiO]-1; O replacing (OH+F) is calculated as equal to 2*Ti apfu according to the exchange vector [TiO2]1[Mg(OH)2]-1 (akin to the “oxo” correction recommended for normalizing titaniferous amphiboles [Hawthorne et al., 2012: Appendix III]). These adjustments were undertaken to hopefully minimize the error introduced into the Fe3+/∑Fe calculation. Study of the light element content of these humite group minerals (and also possibly in any accompanying olivine) would be desirable. Samples FKM-36, FKM-112 and FKM-184 are additional examples of the high grade Franklin marble from the adjoining Sussex Co., NJ/Orange Co., NY area that contain humite group minerals.
(unpolarized light)

mineral representative mineral compositions in FKM-8
norbergite (Mg2.97Fe2+0.02Ti0.01)[Si0.99B0.01O3.99(OH)0.01](F1.57[OH]0.42O0.01)
chondrodite (Mg3.84Fe2+0.10Fe3+0.05)[Si1.94B0.05O7.95(OH)0.05](F1.56[OH]0.44O0.01)
fluoro-pargasite (Na0.72K0.07Sr0.03Ca0.020.16)Ca2.00(Mg4.02Al0.75Fe3+0.08Ti0.06V0.05Cr0.01)
[Si5.96Al2.04O22](F1.08[OH]0.78O0.12Cl0.02)
tremolite (Na0.070.93)(Ca1.98Na0.02)(Mg4.88Fe2+0.08Fe3+0.02Al0.01)[Si7.91Al0.09O22]([OH]1.27F0.72)
phlogopite (K0.52Ba0.24Na0.10Ca0.010.13)(Mg2.90FeT0.07Al0.03Ti0.01)[Si2.84Al1.16O10]([OH]1.20F0.79)
clinochlore (Mg4.61Al1.14FeT0.160.09)[Si3.00Al1.00O10]([OH]7.52F0.48)

Franklin New Jersey norbergite marble in thin section

same as previous FKM-8 image (under crossed polars).

 




Eifel Germany andradite in thin section

sample: FKM-9
locality: Bellerberg volcano, Ettringen, Mayan, Eifel, Rhineland-Palatinate, Germany.
rock type: metasomatized(?) sanidinite facies meta-calcareous ejectum.
major mineralogy: Gehlenite was reported, but not observed in this thin section. Optically- and BSE-zoned grossular garnet (variably enriched in Ti and Fe3+; some zones show significant schorlomite and andradite components) and abundant vuggy calcite occur in a non-descript, fine-grained matrix probably largely composed of carbonate and various calc-silicates.
(unpolarized light)

mineral representative mineral compositions in FKM-9
grossular (core) (Ca2.94Mg0.04Fe2+0.02Mn2+0.01)(Al0.90Fe3+0.78Ti0.30V0.01)[Si2.71Fe3+0.29O12]
grossular (middle) (Ca2.93Mg0.06Fe2+0.01Mn2+0.01)(Al0.78Ti0.62Fe3+0.54Fe2+0.05V0.01)[Si2.43Fe3+0.57O12]
grossular (rim) (Ca2.93Mg0.03Fe2+0.01Mn2+0.01)(Al1.45Fe3+0.54Ti0.01)[Si2.97Fe3+0.03O12]

Eifel Germany andradite in thin section

same as previous FKM-9 image (under crossed polars).

 




Crestmore California monticellite marble in thin section

sample: FKM-10
locality: Crestmore quarries, Crestmore, Riverside Co., CA, USA.
rock type: high-grade monticellite marble. Contact aureole (high-T low-P; sanidinite(?) facies) metamorphosed siliceous dolostone, with possible additional metasomatic contribution from the causative intrusion.
major mineralogy: Monticellite in carbonate (calcite > dolomite). For comparison, another monticellite-bearing sample featured here, also from Crestmore, is FKM-179.
(unpolarized light)

Crestmore California monticellite marble in thin section

same as previous FKM-10 image (under crossed polars).

 




Greenland sapphirine in thin section

sample: FKM-11
locality: Fiskenæsset, Nuuk, Sermersooq, Greenland.
rock type: sapphirine-gedrite-phlogopite gneiss. Perhaps a granulite equivalent to a K-metasomatized cordierite-anthophyllite rock, or perhaps a granulite facies sepiolitic metapelite or argillic (montmorillonite+kaolinite±chlorite) alteration assemblage?
major mineralogy: Low-Fe sapphirine, “sodic-gedrite” (now disallowed as a name and roughly approximated by a composition along the gedrite-“rootname 1” join, according to the petrologically-inconsistent 2012 IMA update of amphibole nomenclature), pargasite, clinochlore and abundant phlogopite. For comparison, other sapphirine-bearing samples featured here include FKM-23 and FKM-28.
(unpolarized light)

mineral representative mineral compositions in FKM-11
sapphirine (Mg3.71Fe2+0.28)(Al8.71Mg3.14Fe3+0.15)O4[Al8.87Si3.13O36]
gedrite-“rootname 1” join
(Hawthorne et al., 2012)
or “sodic-gedrite”
(Leake et al., 1997)
(Na0.580.42)(Mg1.36Fe2+0.51Ca0.13Mn2+0.01)(Mg3.69Al1.30)[Si6.16Al1.84O22]([OH]1.98F0.02)
pargasite (Na0.52K0.060.42)(Ca1.80Fe2+0.19Mn2+0.01)(Mg3.83Al0.98Fe2+0.18Ti0.01)
[Si6.42Al1.58P0.01O22]([OH]1.94F0.04Cl0.01O0.01)
phlogopite (K0.70Na0.15Ba0.010.14)(Mg2.48Al0.35FeT0.13Ti0.010.03)[Si2.80Al1.20O10]([OH]1.97F0.03Cl0.01)
clinochlore (Mg4.36Al1.37FeT0.190.08)[Si2.74Al1.26O10](OH)8.00

Greenland sapphirine in thin section

same as previous FKM-11 image (under crossed polars).

 




Broken Hill gahnite in thin section

sample: FKM-12
locality: Nine Mile nine, Broken Hill district, Yancowinna Co., NSW, Australia.
rock type: gahnite-metaquartzite. Granulite facies possible Zn-rich siliceous volcanogenic meta-exhalite(?)
major mineralogy: Abundant gahnite, slightly altered to an unidentified low-Zn sheet silicate, with sparse ilmenite, in quartz. For comparison, another gahnite-bearing sample featured here (admixed with sulfides rather than quartz) is FKM-178. Additionally, several of the Franklin, NJ samples show a somewhat atypical orange to yellow gahnite (e.g. FKM-45 and FKM-48).
(unpolarized light)

mineral representative mineral compositions in FKM-12
ilmenite (Fe2+0.92Zn0.05Mn2+0.02)Ti1.01O3
gahnite (Zn0.67Fe2+0.25Mg0.07)Al2.00O4

Broken Hill gahnite in thin section

same as previous FKM-12 image (under crossed polars).

 




Merelani Tanzania tanzanite in thin section

sample: FKM-13
locality: Merelani Hills, Lelatema Mtns., Simanjiro district, Manyara region, Tanzania.
rock type: zoisite-quartz “skarn”. Retrograde amphibolite facies overprint of a granulite facies calc-silicate; possibly a meta-marl, with accompanying metasomatism. Specimens such as this with coarse tanzanite (and those with coarse tsavorite garnet… see sample FKM-1, also from Merelani) are reported to occur in locally “low pressure” pockets and veins.
major mineralogy: Abundant quartz with subordinate V-bearing zoisite (“tanzanite”). Scattered diopside, fluorite, V-bearing grossular (particularly as inclusions in zoisite) and graphite are present. The sample is vuggy and heavily fractured, with abundant fine-grained alteration/cementation material (calcite ± halloysite?) filling fractures, along with patches of unidentified Fe-oxides, a separate Mn-oxide, and minor amounts of an Fe-rich sheet silicate that appears to normalize to an unusual (and perhaps new) Ca-dominant stilpnomelane.
(unpolarized light)

mineral representative mineral compositions in FKM-13
grossular (most V-rich) (Ca2.85Mn2+0.08Mg0.06)(Al1.31V0.56Cr0.08Ti0.03Mg0.01)[Si3.02O12]
grossular (most Al-rich) (Ca2.88Mn2+0.07Mg0.04)(Al1.61V0.32Cr0.04Ti0.02Mg0.01)[Si3.02F0.01O11.99]
zoisite Ca0.98Ca1.00Al1.00Al1.00(Al0.93V0.06Cr0.01)O[Si2.00O7][Si1.00O4](OH)
diopside (Ca0.99Na0.01)(Mg0.95Al0.09V0.01)[Si1.97Al0.03O6]
“Ca-stilpnomelane” (Ca0.55Na0.05K0.020.37)(FeT6.92Mg0.32Zn0.09Ni0.05MnT0.01V0.010.60)
[Si11.50Al0.43Fe3+0.08O~30](OH)~6 . ~4.5H2O

Merelani Tanzania tanzanite in thin section

same as previous FKM-13 image (under crossed polars).

 




Langesundfjord Norway astrophyllite syenite in thin section

sample: FKM-14
locality: Langesundfjorden, Larvik, Vestfold, Norway.
rock type: alkali feldspar syenite. Neither quartz nor any feldspathoid was observed in the thin section, so the sample appears to be critically silica-saturated (on the quartz/foid boundary).
major mineralogy: Coarse astrophyllite with scattered variable composition patches and swirls, locally sufficiently Nb-rich to be niobophyllite. Within the astrophyllite are scattered tiny grains of an unidentified Nb-rich mineral. The other abundant minerals in the thin section are aegirine, microcline and albite. One finely- and complexly-zoned Na+REE-rich apatite is present (this grain was initially misidentified as analcime… see note below). In what appears to be a more-erratically zoned overgrowth of apatite, abundant inclusions of substituted(?) “calciobritholite-(Ce)” are scattered along the apatite outer edges and along cracks. Measured Si+P alone fail to fill the “T” site, so an additional light “T” site cation such as boron (so grading compositionally towards tritomite-(Ce), which is reported from numerous Langesundfjorden localities), or possibly carbon, seems likely to be present; in this case, adding in 0.16 apfu estimated B simultaneously fills the “T” site, provides overall charge balance, and brings the analytical total to 100.03 wt%. Sparse scattered small in-fillings of what appear to be a zeolite (possibly tetranatrolite? [material seems too Ca-rich to be natrolite]) are also present. The characterization and analysis of this sample offered several good learning experiences. Astrophyllite group minerals can be challenging to analyze and normalize, in part due to potential vacancies, the possibility of interlayer H2O, variable transition metal valences, variable O for F+[OH] substitution in the φ anion site, and the likely occurrence of rare elements (e.g. Rb, Cs, Ta, Hf) that may be overlooked in routine analytical protocols. For the normalizations of the astrophyllite group mineral analyses presented here, a somewhat modified approach to that suggested in Piilonen et al., 2003 was adopted. Rather than an anion-based normalization, the normalization routine used here was based on ∑(T) = 8, where Si, B, Be, P, S, Ge, As and Al were considered to be the “T” site cations. The “D” site was subsequently populated with Nb, Ta, Zr, Hf and Sn, and then filled with Ti up to 2.00 apfu; excess Ti (typically less than 0.05 apfu) was carried over to the “C” site. Rb, Cs, Hf and Ta were not measured (to date… these may be evaluated later by LA-ICP-MS), but were presently estimated from a crude average of the Langesundfjorden samples described in Piilonen et al., 2003. As Piilonen et al., 2003 also observed with their analyses, the analytical totals reported here are similarly a bit low; these low totals were slightly improved by assuming that cation deficiencies in the “A” site were filled with interlayer H2O. An additional adjustment was made in the φ anion site occupancy based on the measured Nb+Ta content: [OH] is replaced by O = 0.5*[Nb+Ta] apfu to account for the charge imbalance resulting from the partial replacement of [Ti+Zr+Hf+Sn]4+ with [Nb+Ta]5+. Full replacement of [4+] cations with [5+] cations in the “D” site would additionally require the replacement of one [Fe2++Mn2+] with Na in the “C” site (akin to what is observed in magnesium-astrophyllite); hence, a properly charge-balanced niobophyllite end-member formula (no commas!) should be given as K2Na[Na(Fe2+)6]Nb2[Si8O26](OH)4O. Another promising outcome of this normalization routine is that after the addition of estimated Rb & Cs and the partial replacement of [OH] by O, the resultant calculated Fe3+/∑Fe ratio is in the range of 0.01 to 0.05, consistent with the Mössbauer-derived values measured for the Norwegian samples in Piilonen et al., 2003.
 
*Note: prior to examining this thin section on the microprobe, the apatite in this sample was originally thought to be analcime, and is misidentified as such in Isotropic Minerals in Thin Section; I regret the error, and offer a correction here. But there’s also a valuable lesson to be learned from this mistake. Experienced petrographers tend to identify many common minerals by sight, and may forego certain optical tests when an unknown mineral appears familiar. However, especially in atypical “exotic” rocks, relying on familiarity alone can sometimes lead to surprising misidentifications, as was the case here. Several atypical visual features of the unknown mineral helped contribute to its misidentification; indeed, for it to have been apatite rather than analcime, the single crystal in this sample would have had to have been both texturally and optically anomalous (and indeed it was!) First, that it is the only apatite in the thin section is perhaps unusual. It is also not euhedral, and is instead oddly interstitial between larger astrophyllite and microcline crystals. Optically it is essentially isotropic (probably primarily due to crystal orientation, although chemical substitutions also affect the refractive indices), but shows faint very low birefringence sectors (this effect is presumably due to its marked compositional zoning). It also shows moderate relief. All of these properties, along with the noted occurrence of analcime with astrophyllite at several Langesundfjorden localities, seemed indicative of “familiar” analcime. Critically, however, the nature of the moderate relief was not determined (for example, by observing the movement of the Becke line against the adjacent feldspar): analcime has moderate negative relief whereas apatite has moderate positive relief. That simple but commonly neglected test would have readily eliminated analcime as a possibility (although apatite would almost certainly not have been an alternative identification given its other anomalous properties… so ultimately this grain was destined for the microprobe!) It is quite likely that the significant Na+REE substitution for Ca in this apatite (along with the marked zoning) had a modifying effect on its physical and optical properties. But that realization only emphasizes an important and humbling lesson: especially in unusual rocks, a “familiar” mineral may not always be what it seems, and the effort of extra care is never for naught!
(unpolarized light)

mineral representative mineral compositions in FKM-14
fluorapatite (low z) (Ca4.61Sr0.09Na0.06Y0.050.19)[P3.00O12]F1.07
fluorapatite (mod z) (Ca4.54Na0.15Y0.12Sr0.04Gd0.01[HREE]0.010.13)[P3.00O12](F0.91[OH]0.09)
fluorapatite (mod-high z) (Ca4.36Na0.29Y0.13Ce0.06Nd0.03[HREE]0.03Sr0.02La0.02Gd0.02Pr0.01Sm0.010.02)
[P3.00O12](F0.93[OH]0.07)
“calciobritholite-(Ce)” (Ca1.64Ce1.46Nd0.85La0.46Pr0.21Sm0.12Na0.12Gd0.04Y0.04Sr0.04[HREE]0.03)
[Si2.46P0.38B~0.16O12]([OH]0.55F0.44Cl0.01)
aegirine
(in astrophyllite)
(Na0.94Ca0.05)(Fe3+0.86Fe2+0.06Al0.05Ti0.02)[Si1.99Al0.01O6]
aegirine
(in microcline; main)
(Na0.91Ca0.08Mn2+0.01)(Fe3+0.81Fe2+0.10Al0.06Ti0.02Mg0.01)[Si1.99Al0.01O6]
aegirine
(in microcline; high z core)
(Na0.89Ca0.12)(Fe3+0.83Fe2+0.10Al0.02Ti0.02Mg0.01Mn2+0.01Zr0.01)[Si1.98Al0.02O6]
astrophyllite-dominant
astrophyllite group ss
(main)
(K1.51Rb0.10?Na0.03Ba0.01Cs0.01?[H2O]0.32?)(Na0.87Ca0.13)
(Na0.36Fe2+4.00Mn2+2.32Fe3+0.22Ti0.05Mg0.03V0.01)(Ti1.21Nb0.77Zr0.01Sn0.01)
[Si7.81Al0.19O26](OH)4(F0.46O0.39[OH]0.15)
astrophyllite-dominant
astrophyllite group ss
(low z swirls in main)
(K1.45Na0.35Ba0.01[H2O]0.19?)(Na0.96Ca0.04)
(Na0.04Fe2+5.53Mn2+1.29Mg0.06Ti0.04Fe3+0.02V0.01)(Ti1.86Nb0.12Zr0.01Sn0.01)
[Si7.99Al0.01O26](OH)4(F0.70[OH]0.23O0.06)
niobophyllite-dominant
astrophyllite group ss
(high z swirls in main)
(K1.46Rb0.11?Na0.02Ba0.01Cs0.01?[H2O]0.39?)(Na0.99Ca0.01)
(Na0.48Fe2+3.69Mn2+2.57Fe3+0.17Mg0.05Ti0.03V0.02)(Nb1.26Ti0.74)
[Si7.97Al0.03O26](OH)4(O0.63F0.22[OH]0.15)
microcline (K0.97Na0.04)[Si2.99Al1.01O8]
albite Na1.02[Si2.99Al1.01O8]
tetranatrolite? ([Na2]0.80Ca0.31)[Al2.30Si2.70O10] . ~2.2H2O

Langesundfjord Norway astrophyllite syenite in thin section

same as previous FKM-14 image (under crossed polars).

 




Laytonville California stilpnomelane in thin section

sample: FKM-15
locality: Laytonville quarry, Laytonville, Mendocino, Co., CA, USA.
rock type: spessartine-stilpnomelane-metaquartzite. Blueschist facies ferruginous metaquartzite.
major mineralogy: Scattered stilpnomelane and abundant tiny spessartine, in quartz. This sample was originally reported to contain zussmanite, but it does not (however, see FKM-147 from the same locality, which does contain abundant zussmanite). Stilpnomelane is a challenging mineral to normalize, owing to possible vacancies in the A and M sites, likely Fe3+ and/or Mn3+ in the M site, and variable hydroxyl and excess water. For this sample, the stilpnomelane is normalized to three simplifying assumptions: (a) 20 T+M cations (permits no vacancies in the M site), (b) 6[OH] per 36 total [O+OH] (this conforms to a sheet silicate T4O10 skeleton and also yields a reasonable M3+/∑M [M = Fe+Mn] ≈ 0.32), and finally (c) 5 moles of excess H2O (which brings the overall total to almost exactly 100 wt%). Although this normalization results in a permissible formula, this material would benefit from additional characterization.
(unpolarized light)

mineral representative mineral compositions in FKM-15
spessartine (Mn2+1.56Fe2+1.10Ca0.27Y0.03Mg0.02Na0.02)(Al1.93Fe3+0.02Mg0.02V0.01Ti0.01)[Si2.95Al0.03P0.02O12]
stilpnomelane (K0.32Ca0.08Na0.06Ba0.050.49)(FeT5.60MnT1.17Mg0.75Al0.39V0.06Cr0.01Ni0.01)[Si10.76Al1.24O~30](OH)~6 . ~5H2O

Laytonville California stilpnomelane in thin section

same as previous FKM-15 image (under crossed polars).

 




Madagascar chrysoberyl in thin section

sample: FKM-16
locality: Tsitondroina, Ikalamavany district, Fianarantsoa province, Madagascar.
rock type: chrysoberyl “amphibolite”. This rock occurs as ~10 cm veins and is likely of metasomatic origin.
major mineralogy: Scattered chrysoberyl in a matrix of partially altered anorthite and amphibole (widely reported in the mineral collector community to be taramite, but in this thin section verified as fluorian pargasite by EPMA). For comparison, another chrysoberyl-bearing sample featured here is FKM-156, although as an Al-rich oxide in an amphibole+anorthite rock, this particular sample also bears some resemblance to the corundum-bearing amphibolite sample FKM-24.
(unpolarized light)

mineral representative mineral compositions in FKM-16
chrysoberyl analysis pending
pargasite (Na0.74K0.17Ca0.020.07)Ca2.00(Mg4.06Al0.67Fe3+0.15Fe2+0.11)[Si6.27Al1.73O22]([OH]1.09F0.86Cl0.04)
anorthite (Ca0.98Na0.02)[Si2.00Al2.00O8]

Madagascar chrysoberyl in thin section

same as previous FKM-16 image (under crossed polars).

 




Lovozero Kola Russia lamprophyllite syenite in thin section

sample: FKM-17
locality: Sengischorr Mountain, Lovozero massif, Kola Peninsula, Murmanskaja Oblast’, Russia.
rock type: nepheline syenite.
major mineralogy: specimen acquired for lamprophyllite. Based on petrography, in addition to lamprophyllite, abundant eudialyte, aegirine, alkali feldspar and nepheline are present. The nepheline shows alteration rims, presumably of cancrinite.
(unpolarized light)

Lovozero Kola Russia lamprophyllite syenite in thin section

same as previous FKM-17 image (under crossed polars).

 




Pargas Finland diopside marble in thin section

sample: FKM-18
locality: Pargas, Finland.
rock type: high grade meionite-diopside marble. The host rock is reported to be a “limestone” interbedded between a diopside amphibolite and a garnet-cordierite gneiss (see Chapter 2 [p. 54] in The Mines and Quarries of Finland [1954]). The characterization of the rock as a limestone coupled with the abundance of K and F indicates metamorphism was probably not entirely isochemical, and suggests the possibility of accompanying metasomatism.
major mineralogy: Abundant diopside, minor fluorite and meionitic scapolite (partially altered), in calcite. The sample was originally reported to contain pargasite, but this thin section contains no amphibole. However, pargasite and K- and F-rich pargasite family amphiboles do occur at Pargas (the type locality).
(unpolarized light)

mineral representative mineral compositions in FKM-18
diopside (Ca0.99Na0.02)(Mg0.66Fe2+0.24Fe3+0.04Al0.04Ti0.01Mn2+0.01)[Si1.92Al0.08O5.99F0.01]
meionite (Ca2.52Na0.46K0.02Mg0.01)[Si6.45Al5.53Fe3+0.01O24] . Ca1.01(CO3)1.01

Pargas Finland diopside marble in thin section

same as previous FKM-18 image (under crossed polars).

 




Gjerdingen Norway elpidite ekerite in thin section

sample: FKM-19 (separate specimen from sample FKM-19b)
locality: Gjerdingselva, Nordmarka, Lunner, Oppland, Norway.
rock type: “elpidite ekerite” (soda-granite).
major mineralogy: Quartz and K-feldspar (perthitic and heavily altered), with riebeckite, aegirine, kupletskite and elpidite.
(unpolarized light)

Gjerdingen Norway elpidite ekerite in thin section

same as previous FKM-19 image (under crossed polars).

 




Gjerdingen Norway elpidite ekerite in thin section

sample: FKM-19b (separate specimen from sample FKM-19)
locality: Gjerdingselva, Nordmarka, Lunner, Oppland, Norway.
rock type: “elpidite ekerite” (soda-granite).
major mineralogy: Quartz and K-feldspar (perthitic and heavily altered), with riebeckite, aegirine, kupletskite and elpidite.
(unpolarized light)

Gjerdingen Norway elpidite ekerite in thin section

same as previous FKM-19b image (under crossed polars).

 




zincite willemite franklinite and gageite in thin section

sample: FKM-20
locality: Franklin mining district, Sussex Co., NJ, USA.
rock type: zincite-franklinite-willemite “marble”. Granulite facies Zn-Mn metasomatite.
major mineralogy: Classic Franklin-type assemblage of zincite, franklinite, and willemite (partially altered to gageite), all hosted in calcite.
(unpolarized light)

zincite willemite franklinite and gageite in thin section

same as previous FKM-20 image (under crossed polars).

 




Greenwood mine New York hastingsite amphibole in thin section

sample: FKM-21
locality: Greenwood mine, Tuxedo, Orange Co., NY, USA.
rock type: K-Fe metasomatite associated with hydrothermal Fe-oxide mineralization. The occurrence of metasomatic K-Cl-bearing hastingsite (sensu lato) with magnetite and apatite is characteristic of the ore zone in many IOCG (iron-oxide-Cu-Au) systems (Mazdab, 2003).
major mineralogy: Calcic amphibole is the dominant mineral in this sample. It is reported as potassic-fluoro-hastingsite (Lupulescu et al., 2009), but in this thin section the examined amphibole was verified by EPMA as Cl-F-bearing potassic-magnesio-hastingsite. This amphibole is broadly similar in composition, and of similar occurrence, to the hastingsite in sample FKM-33. Magnetite, apatite and a plagioclase-quartz symplectite are also abundant. Subordinate orthoclase is also present, both as small masses intergrown with the symplectite, and as larger crystals of “perthite” (possibly relict from an earlier igneous or hydrothermal event). Additional minor minerals present include laths of ilmenite in the magnetite, abundant very tiny monazite inclusions in the apatite, and some cpx (patchy zoned augite to diopside) in the amphibole (relict, possibly from an earlier higher temperature hydrothermal event).
(unpolarized light)

mineral representative mineral compositions in FKM-21
ilmenite (Fe2+0.96Mn2+0.03)Ti1.00O3
magnetite Fe2+1.00(Fe3+1.96Al0.02Ti0.01Fe2+0.01)O4
monazite-(Ce) (Ce0.49La0.34Nd0.07Pr0.04Ca0.03)[P1.00Si0.02O4]
fluorapatite (Ca4.92Ce0.02La0.01Nd0.01Y0.01Na0.01)[P2.98Si0.03O12](F0.68[OH]0.30Cl0.02)
diopside-dominant cpx ss (Ca0.87Mg0.07Na0.04Mn2+0.01)(Mg0.48Fe2+0.43Fe3+0.07Al0.02)[Si1.94Al0.06O6]
augite-dominant cpx ss (most Mg-rich) (Ca0.84Mg0.11Na0.04Mn2+0.01)(Fe2+0.46Mg0.46Fe3+0.05Al0.03)[Si1.96Al0.04O6]
augite-dominant cpx ss (most Fe-rich) (Ca0.70Mg0.25Na0.03Mn2+0.02)(Fe2+0.58Mg0.32Fe3+0.06Al0.03)[Si1.94Al0.06O6]
potassic-magnesio-hastingsite (K0.42Na0.310.27)(Ca1.79Na0.21)(Mg1.89Fe2+1.66Fe3+1.08Al0.26Ti0.07Mn2+0.03)
[Si6.12Al1.87O22]([OH]1.01F0.53Cl0.32O0.15)
orthoclase (with symplectite) (K0.87Na0.10Ba0.01)[Si2.96Al1.03O8]
“perthite” (orthoclase host) (K0.88Na0.08)[Si2.98Al1.02O8]
“perthite” (“oligoclase” lamellae) (Na0.72Ca0.29K0.01)[Si2.67Al1.32Fe3+0.01O8]
“andesine” (symplectite) (Na0.69Ca0.31K0.01)[Si2.66Al1.34O8]

Greenwood mine New York hastingsite amphibole in thin section

same as previous FKM-21 image (under crossed polars).

 




Cascade Canyon California corundum sapphire in thin section

sample: FKM-22
locality: Cascade Canyon, San Gabriel Mtns., Los Angeles Co., CA, USA.
rock type: test.
major mineralogy: specimen acquired for corundum.
(unpolarized light)

Cascade Canyon California corundum sapphire in thin section

same as previous FKM-22 image (under crossed polars).

 




India sapphirine in thin section

sample: FKM-23 (billet from Univ. Arizona petrology collection, courtesy of J. Ganguly)
locality: Anantagiri, Eastern Ghats belt, Anantagiri district, Andhra Pradesh, India.
rock type: sapphirine-opx-garnet-cordierite gneiss. Granulite facies (sapphirine zone) metapelite.
major mineralogy: Sapphirine (mostly mantled by sillimanite coronas), with cordierite, almandine, orthopyroxene, as well as abundant quartz, feldspar (both plagioclase and orthoclase), scattered rutile (also with ~748 ppm Cr) and hercynite, and minor monazite. For added interest, a number of the included analyses represent mineral pairs (where the measurements were taken adjacent to other minerals). Additional sapphirine-bearing samples featured here include FKM-11 and FKM-28, for comparison.
(unpolarized light)

mineral representative mineral compositions in FKM-23
spinel (enclosed in garnet) (Mg0.56Fe2+0.41Zn0.02)(Al1.92Fe3+0.06Cr0.01)O4
hercynite (rimmed by sillimanite) (Fe2+0.56Mg0.41Zn0.02)(Al1.89Fe3+0.08Cr0.02)O4
hercynite (adjacent to sapphirine) (Fe2+0.54Mg0.44Zn0.02)(Al1.92Fe3+0.06Cr0.02)O4
ilmenite (Fe2+0.89Mg0.09Fe3+0.01)(Ti0.99Fe3+0.01)O3
rutile Ti0.99O2
monazite-(Ce) (Ce0.48La0.23Nd0.14Pr0.05Th0.04Ca0.03Sm0.01)[P0.98Si0.01O4]
pyrope (adjacent to spinel) (Mg1.46Fe2+1.41Ca0.09Mn2+0.04)(Al1.92Fe3+0.08)[Si3.00O12]
almandine (adjacent to biotite) (Fe2+1.51Mg1.35Ca0.10Mn2+0.04)(Al1.94Fe3+0.06)[Si3.00O12]
sillimanite (Al1.98Fe3+0.01)O[Si0.98Al0.02O4]
cordierite (adjacent to sapphirine) (Mg1.67Fe2+0.27Fe3+0.06)(Al2.98Fe3+0.02)[Al1.08Si4.92O18] . Na0.01
“hypersthene” (Mg0.99Mn2+0.01)(Fe2+0.61Mg0.19Al0.14Fe3+0.06Ti0.01)[Si1.79Al0.21O6]
sapphirine (adjacent to hercynite) (Mg2.23Fe2+1.74Mn2+0.01Ni0.01Ca0.01Na0.01)(Al8.36Mg3.04Fe3+0.52Cr0.05V0.02Ti0.01)O4[Al8.96Si3.04O36]
sapphirine (adjacent to cordierite) (Mg2.21Fe2+1.77Mn2+0.01Ni0.01)(Al8.40Mg3.04Fe3+0.43Cr0.09V0.02Ti0.02)O4[Al8.97Si3.03O36]
sapphirine (adjacent to biotite) (Mg2.64Fe2+1.33Mn2+0.01Ni0.01K0.01)(Al8.42Mg3.11Fe3+0.41Cr0.03Ti0.02V0.01)O4[Al8.90Si3.10O36]
phlogopite (adjacent to garnet+sapphirine) (K0.93Na0.010.06)(Mg2.20FeT0.41Ti0.27Al0.11)[Si2.82Al1.18O10]([OH]1.02O0.55F0.42Cl0.01)
phlogopite (most Fe-rich) (K0.940.06)(Mg1.90FeT0.63Ti0.26Al0.18Cr0.01V0.010.01)
[Si2.82Al1.18O10]([OH]1.14O0.52F0.32Cl0.02)
orthoclase (K0.94Na0.02Ca0.01Sr0.01)[Si2.94Al1.05P0.01O8]
“andesine” (Na0.64Ca0.33K0.03)[Si2.62Al1.37O8]

India sapphirine in thin section

same as previous FKM-23 image (under crossed polars).

 




Madagascar ruby tschermakite and anorthite amphibolite in thin section

sample: FKM-24
locality: Fotodrevo area, Ejeda commune, Ampanihy district, Tuléar province, Madagascar.
rock type: corundum amphibolite. Granulite facies amphibolite (estimated at below ~900° C and below ~10 kbars, according to experimental phase relations; estimated at 820°C and 7.1 kbars [hence consistent with the phase equilibria] using the edenite-richterite formulation of Holland and Blundy, 1994 [run at several of the highest permitted An content feldspar compositions and then further extrapolated to An0.94 and An0.95] coupled with Anderson et al., 2008… the alternative edenite-tremolite formulation gives 935°C and 2.1 kbars [a bit hot to be consistent with the phase equilibria]; lastly, estimated at 970° C and 3 kbars from the single-mineral amphibole thermobarometry equations of Ridolfi et al., 2010 [but this thermobarometer seems to commonly yield higher T & P estimates relative to that obtained from most amphibole-plagioclase pairs, and in this case is also too hot to be consistent with the phase equilibria]). This sample is essentially a lower pressure version of sample FKM-68. Another also similar corundum-bearing amphibolite is sample FKM-158, but that rock contains abundant garnet and its plagioclase is much more Na-rich (oligoclase). This sample also seems to have a higher bulk Mg/(Mg+Fe) ratio than FKM-158.
major mineralogy: Corundum (in the hand sample, but not in this thin section) in a matrix of tschermakite (near the tschermakite/ferri-tschermakite composition boundary) and anorthite. Minor alteration chlorite also occurs in the sample.
(unpolarized light)

mineral representative mineral compositions in FKM-24
tschermakite (Na0.18K0.030.79)(Ca1.67Na0.33)(Mg2.97Al1.04Fe3+0.94Cr0.02Mn3+0.02Ti0.02)[Si6.07Al1.93O22]([OH]1.97O0.03)
anorthite (Ca0.95Na0.05Sr0.01)[Si2.03Al1.97O8]
clinochlore (Mg3.82Al1.41FeT0.65Ni0.010.11)[Si2.66Al1.34O10](OH)8.00

Madagascar ruby tschermakite and anorthite amphibolite in thin section

same as previous FKM-24 image (under crossed polars).

 




Afghanistan lazurite in thin section

sample: FKM-25
locality: Sar-e-Sang, Koksha valley, Badakhshan province, Afghanistan.
rock type: lazurite marble. Upper amphibolite to granulite facies calcareous meta-evaporite, almost certainly with superimposed autologous(?) metasomatism.
major mineralogy: Calcite-dominant with bands of lazurite, forsterite, diopside, phlogopite, nepheline and pyrite. The thin section was cut too thin, and the observed birefringence values of the anisotropic minerals are much lower than what one is accustomed to seeing. Sample FKM-155, also from Sar-e-Sang, may represent an evaporite facies depositionally-related to the carbonate-dominated facies represented by this sample.
(unpolarized light)

Afghanistan lazurite in thin section

same as previous FKM-25 image (under crossed polars).

 




Merelani Tanzania tremolite diopside and mukhinite in thin section

sample: FKM-26
locality: Merelani Hills, Lelatema Mtns., Simanjiro district, Manyara region, Tanzania.
rock type: diopside “skarn”. Granulite facies calc-silicate with retrograde amphibolite facies overprinting; possibly a meta-marl, with accompanying metasomatism.
major mineralogy: Mostly vanadian diopside with minor vanadian A-site-vacant calcic amphibole (straddling the nomenclature boundary between tremolite and magnesio-hornblende), graphite, sparse zoned titanite (up to 0.15 apfu V; more enriched in V than titanite from sample FKM-1, also from Merelani) and scattered calcite. Rare chromian mukhinite and sulvanite were observed during microprobe examination of the original polished billet but were not found in this prepared thin section (however, mukhinite is also present in sample FKM-92, and so may be more widespread in V-rich metasomatic rocks than typically reported). There’s also a mineral present in the original billet (but also not observed in this prepared thin section) with a chemistry atypical of the other identified minerals. The major element composition is (all in wt%): F 2.6; Al 6.7; Si 15.5; Ca 25.4; V 9.2; Cr 0.3. Adding in minor Ti, Mg, Y and Sc (the sum of these totals to less than 0.36 wt%, most of which is Ti), it can be normalized to possibly an unusual vanadian vesuvianite (although the various site fillings are rather poor… total with estimated H2O ~98.7 wt%), or alternatively, and with better site fillings, to a vanadian fluor-hydrogrossular (total with estimated H2O ~99.2 wt%). More of this material will be sought in what remains of the billet to hopefully improve its characterization. The analyses listed below are taken from both the original polished billet and from the thin section subsequently prepared from it. Although the minor mineralogy between the two materials somewhat differs due to slight sample heterogeneity, for completeness, the mineral list encompasses both materials.
(unpolarized light)

mineral representative mineral compositions in FKM-26
“fluor-hydrogrossular”? (Ca2.97Y0.01)(Al1.12V0.84Cr0.03Ti0.02)[Si2.57Al0.040.39O10.44(OH)0.91F0.65]
titanite (core) (Ca0.98Y0.02[REE]0.01)(Ti0.83V0.09Al0.08)(O0.92F0.05[OH]0.03)[Si0.99Al0.01O4]
titanite (rim) (Ca0.98Y0.01[REE]0.01)(Ti0.78V0.13Al0.08)(O0.93F0.04[OH]0.03)[Si1.01O4]
mukhinite (needs re-analysis) Ca1.00Ca0.93(Al0.52V0.24Cr0.22)Al1.00(V0.63Mg0.32Mn3+0.05)(O0.91F0.09)[Si2.05O7][Si1.03O4](OH)
diopside (Ca0.94Na0.05Mg0.01)(Mg0.89Al0.06V0.04)[Si1.95Al0.05O6]
tremolite-rich Ca-amph ss (Na0.09K0.040.87)(Ca1.94Na0.06)(Mg4.51V0.31Al0.14Sc0.01Ti0.01Cr0.01Mn2+0.01)
[Si7.51Al0.49O22]([OH]1.74F0.25O0.01)
magnesio-hornblende-rich
Ca-amph ss
(Na0.16K0.040.80)(Ca1.99Na0.01)(Mg4.49V0.26Al0.20Ti0.03Cr0.02Mn2+0.01)
[Si7.43Al0.57O22]([OH]1.72F0.22O0.05)
phlogopite (K0.86Na0.010.13)(Mg2.75Al0.11V0.08Ti0.01Cr0.010.04)[Si3.00Al1.00O10]([OH]1.32F0.65O0.03)
clinochlore (Mg4.56Al0.99V0.26Cr0.030.16)[Si3.01Al0.99O10]([OH]7.83F0.16)

Merelani Tanzania tremolite diopside and mukhinite in thin section

same as previous FKM-26 image (under crossed polars).

 




Kipawa Canada eudialyte in thin section

sample: FKM-27
locality: Kipawa alkaline complex, Les Lacs-du-Témiscamingue, Abitibi-Témiscamingue, Québec, Canada.
rock type: metamorphosed alkali syenite.
major mineralogy: This attractive coarse-grained red, black and white rock is composed primarily of eudialyte, K-bearing amphibole approximately along the fluoro-magnesio-arfvedsonite/fluoro-richterite join, and two alkali feldspars (albite and microcline, the latter sometimes showing evidence of a partially obliterated weakly perthitic texture). Scattered fluorite is also present (commonly as rims between eudialyte and feldspar), as is minor aegirine-augite. Rare aluminocerite-(Ce) occurs as inclusions in amphibole. Analytical notes: (1) the analytical total including estimated H2O and estimated HREE is only 95.62 wt% for the aluminocerite-(Ce), so this material warrants additional analyses; (2) the Li content of the amphibole has not been verified by ICP-MS or SIMS, but the addition markedly improves the overall charge balance, total, and the VIM-site occupancy; (3) due to potential vacancies in multiple sites, the possibility of variable OH, H2O and even H2O+, and the common issue of multiple valences of Fe and Mn, eudialyte is a challenging mineral to normalize. The normalization routine used here is ∑(T+Z+M3+M4)=29, although this still requires a number of additional assumptions, including reasonable estimates of Fe3+/∑Fe and OH/(O+OH) ratios; additionally, Hf has not been measured here and is assumed to be 0.01*Zr (wt%). Estimates for Fe3+/∑Fe, water content and HREE abundances were based on analytical data provided by Schilling et al., 2011 [← subscription required] for Kipawa eudialyte. The structural formulas presented below are based on typical cation site occupancies (for an overview of the eudialyte group, see Johnsen et al., 2003), but the cation partitionings have not been verified by X-ray work. For simplicity, the presented structural formulas only account for the possibilities of vacancies in the N-sites and potentially in M2, although vacancies may exist in other sites too. While the overall normalization results in permissible formulas, this material would benefit from additional characterization. Hence, given these caveats, when comparing these eudialyte compositions to those from other samples presented here, it is most prudent to look at the sum of each element, rather than the plausible but explicitly unverified site assignments. Sample FKM-65, also from the Kipawa complex, is similar to this sample but also contains significant mosandrite.
(unpolarized light)

mineral representative mineral compositions in FKM-27
aluminocerite-(Ce)
(low analytical total;
re-analysis warranted)
(Ca3.05Ca2.92La2.02Nd0.54Pr0.26Na0.06Sr0.05Y0.05Sm0.02Gd0.01[HREE]0.01)
(Al0.69Fe3+0.13Mg0.13MnT0.02Ti0.02)[Si3.00O12][Si3.93Al0.07O12(OH)4](OH)3
eudialyte
(very weakly higher z;
estimated z̄ ≈ 15.23)
(Na9.232.77?)(Na1.07Ca0.68Y0.66[HREE]~0.19Ce0.13La0.08Nd0.05Gd0.05Sr0.05Sm0.02Pr0.02)
Ca6.00(Na1.31Fe2+~1.03Mn2+0.52Fe3+~0.10Mg0.04)(Zr2.80Nb0.11Ti0.06Hf~0.03Ta~0.01)
(Si0.92Nb0.04Al0.04)[(Si1.00O)(Si9.00O27)2][Si3.00O9]2([H2O]~2.20O~0.43[OH]~0.24Cl0.13)(Cl0.94F0.06)
eudialyte
(very weakly lower z;
estimated z̄ ≈ 15.07)
(Na9.003.00?)(Na1.00Ca0.76Y0.69[HREE]~0.19Ce0.12La0.07Sr0.05Gd0.05Nd0.04Sm0.02Pr0.01)
Ca6.00(Na1.06Fe2+~0.86Mn2+0.53Fe3+~0.09Mg0.040.41?)(Zr2.77Ti0.14Nb0.05Hf~0.03Ta~0.01)
(Si0.88Al0.06Nb0.05)[(Si1.00O)(Si9.00O27)2][Si3.00O9]2([H2O]~2.54Cl0.34[OH]~0.11)(Cl0.55F0.45)
aegirine-augite (Na0.52Ca0.48)(Fe3+0.46Mg0.31Fe2+0.10Al0.04Mn2+0.03Ca0.03Ti0.01Zr0.01)[Si1.98Al0.02O6]
~[fluoro-magnesio-arfvedsonite]-
[fluoro-richterite] join
(Leake et al., 1997)
(Na0.61K0.39)(Na1.40Ca0.60)(Na~0.09Mg3.06Fe3+0.82Fe2+0.50Mn2+0.14Al0.10Zn0.03Ti0.01Zr0.01~0.24)
[Si8.00O22](F1.44[OH]0.54O0.02)
microcline (K0.93Na0.05)[Si2.97Al1.02O8]
albite (Na1.00K0.01)[Si2.98Al1.02Fe3+0.01O8]

Kipawa Canada eudialyte in thin section

same as previous FKM-27 image (under crossed polars).

 




Madagascar sapphirine in thin section

sample: FKM-28
locality: Betroka district, Tuléar province, Madagascar.
rock type: cordierite-opx-sapphirine-phlogopite gneiss. Perhaps a granulite equivalent to a K-metasomatized cordierite-anthophyllite rock, or perhaps a granulite facies sepiolitic/illitic metapelite or argillic (montmorillonite+kaolinite±chlorite) alteration assemblage?
major mineralogy: Sapphirine (in part rimmed by cordierite, which is in turn partially altered to an “Al-rich saponite” that shows a fairly consistent major element content but a seemingly variable water content), Al-rich enstatite, phlogopite and a P-bearing perthitic Na-rich K-feldspar (sanidine?) with oligoclase exsolution lamellae. Scattered large apatite and large zoned monazite are present, as well as minor zircon and secondary zeolitic alteration. For comparison, other sapphirine-bearing samples featured here include FKM-11 and FKM-23.
(unpolarized light)

mineral representative mineral compositions in FKM-28
fluorapatite (Ca4.91Na0.04Fe2+0.01La0.01Ce0.01Nd0.01)[P3.00O12](F0.85[OH]0.09Cl0.07)
monazite-(Ce) (core) (Ce0.42La0.17Nd0.16Th0.11Pr0.05Ca0.04Sm0.02Gd0.01Pb0.01[HREE]0.01Y0.01)[P0.92Si0.07S0.01O4]
monazite-(Ce) (inner rim) (Ce0.41La0.16Nd0.16Th0.11Pr0.05Ca0.04Sm0.01Gd0.01Pb0.01[HREE]0.01Y0.01)[P0.91Si0.08S0.01O4]
monazite-(Ce) (outer rim) (Ce0.42La0.19Nd0.14Ca0.08Th0.07Pr0.05Sm0.01Pb0.01Y0.01)[P1.00Si0.01O4]
cordierite (Mg1.98Fe3+0.02)(Al2.96Fe3+0.04)[Al1.07Si4.93O18] . Na0.01
enstatite Mg1.00(Mg0.75Al0.12Fe2+0.11Fe3+0.02)[Si1.85Al0.15O6]
sapphirine (Mg3.62Fe2+0.37)(Al8.39Mg3.52Fe3+0.07Ti0.01)O4[Al8.49Si3.51O36]
phlogopite (K0.95Na0.05)(Mg2.63Ti0.17FeT0.11Al0.09)[Si2.75Al1.25O10]([OH]1.07F0.58O0.34)
“Al-dominant saponite”?
(low H2O)
(Ca0.12K0.02Na0.01)(Al1.59Mg0.77FeT0.07MnT0.010.57)[Si3.24Al0.76O10]([OH]1.99F0.01) . ~3.3H2O
“Al-dominant saponite”?
(high H2O)
(Ca0.25K0.01Na0.01Ba0.01)(Al1.58Mg0.60FeT0.07MnT0.010.74)[Si3.38Al0.62O10]([OH]1.98F0.02) . ~7.9H2O
“perthite”
(sanidine? host)
(K0.61Na0.38Ca0.02)[Si2.92Al1.06P0.02O8]
“perthite”
(“oligoclase” lamellae)
(Na0.76Ca0.24K0.01)[Si2.71Al1.28P0.01O8]

Madagascar sapphirine in thin section

same as previous FKM-28 image (under crossed polars).

 




Khibiny Kola Russia eudialyte and titanite syenite in thin section

sample: FKM-29
locality: Yukspor Mtn., Khibiny massif, Kola Peninsula, Murmanskaja Oblast’, Russia.
rock type: test.
major mineralogy: specimen acquired for eudialyte and titanite.
(unpolarized light)

Khibiny Kola Russia eudialyte and titanite syenite in thin section

same as previous FKM-29 image (under crossed polars).

 




Woods mine New South Wales serandite and ungarettiite in thin section

sample: FKM-30
locality: Woods mine, Tamworth, Darling Co., NSW, Australia.
rock type: sérandite-ungarettiite-quartz gneiss. Upper amphibolite facies manganiferous metasediment, with possible superimposed Na-metasomatism?
major mineralogy: The mineralogical characterization of this sample has been a challenge. The sample was originally acquired for “kôzulite”, a hydrous amphibole now officially re-named mangano-ferri-eckermannite (or potentially alternatively mangano-mangani-eckermannite, depending on whether Fe3+ or Mn3+ is dominant). However, re-examination of the amphibole in this sample suggests that much of what was previously identified to be “kôzulite” is in fact the anhydrous and optically somewhat similar mangano-mangani-ungarettiite. Note that compositionally, NaNa2(Mn2+2Mn3+3)[Si8O22]O2 (i.e. Mn2+-Mn3+-ungarettiite) is essentially indistinguishable from NaNa2(Mn2+4Mn3+)[Si8O22](OH)2 (i.e. Mn2+-Mn3+-eckermannite) based only on microprobe results, as H content and the overall charge of Mn would have to be determined by other analytical methods. Further complicating the amphibole characterization is that intergrown with the main mangano-mangani-ungarettiite is a K-dominant version that may be a new mineral but is otherwise chemically similar to the main material. Also of note is that the small amount of Li included in the two tabulated amphibole compositions is only an assumption and also needs to be verified by ICP-MS or SIMS; however, the estimated amounts markedly improve the overall normalizations, and would also not be inconsistent with slight solid solution toward leakeite/pedrizite compositions and the occurrence of sugilite at this locality. In addition to the one (or two?) amphibole species present, two (or possibly three?) pyroxenoid species are present (see mineral composition table, below). Crystals which normalize best to rhodonite contain no Na and ~40.3 wt% Mn (the two elements with the greatest differences among the three minerals) and occur as relict rounded grains within crystals which normalize best to sérandite and contain ~6.0 wt% Na and ~30.2 wt% Mn. A third material contains ~3.0 wt% Na and ~35.2 wt% Mn, and normalizes best to natronambulite after the assumption of ~0.16 wt% Li (again, not verified by ICP-MS or SIMS). Natronambulite is not reported from this locality in the mindat.com database, and given that the Mn-rich pyroxenoids also show some overlap in optical properties, this identification should be considered tentative pending further study. These pyroxenoids and amphibole(s) occur with abundant quartz and minor braunite. Rare grains of a new Ba-Na-Mn-phosphate with a seemingly merwinite-like formula (end-member: BaNa2Mn2+[PO4]2) were observed during microprobe examination of an original epoxy mount of this rock. Subsequent examination of this thin section (prepared from a different chunk of the same larger specimen) has not yet yielded more of this material. Overall, this thin section would benefit from further study, and the preparation and examination of additional thin sections from the original larger rock would certainly be worthwhile.
(unpolarized light)

mineral representative mineral compositions in FKM-30
“Ba-Na-Mn2+-PO4
(merwinite structure)?
Ba0.99(Na1.92Sr0.06Ca0.01)Mn2+1.00[P1.99Si0.02O7.87F0.13]
braunite (Mn2+0.94Mn3+0.03Ca0.02Na0.01)Mn3+6.01O8[Si0.98O4]
rhodonite (Mn2+0.73Ca0.29Na0.01)Mn2+1.00Mn2+1.00Mn2+1.00(Mn2+0.90Mn3+0.10)[Si4.95O15]
natronambulite? (Na0.81Li~0.15Ca0.04)(Mn2+0.93Ca0.07)Mn2+1.00Mn2+1.00Mn2+1.00[Si5.00O14](OH)
sérandite (Na0.98Ca0.02)(Mn2+0.98Ca0.02)Mn2+1.00[Si2.99O8](OH)
Mn2+-Mn3+-ungarettiite-rich
oxo-amph ss
(Na0.98K0.01Sr0.01)(Na1.90Li~0.06Ca0.05)(Mn2+2.03Mn3+2.92Fe3+0.01Al0.01Mg0.01Li~0.01)
[Si8.00O22]O2.00
“K-Mn2+-Mn3+-ungarettiite”-rich
oxo-amph ss
(K0.89Na0.11)(Na1.87Li~0.13)(Mn2+1.93Mn3+2.98Fe3+0.03Al0.01Mg0.01Zn0.01Li~0.03)
[Si8.00O22](O1.99F0.01)

Woods mine New South Wales serandite and ungarettiite in thin section

same as previous FKM-30 image (under crossed polars).

 




India corundum ruby in thin section

sample: FKM-31
locality: Mysore district, Karnataka, India.
rock type: corundum-fuchsite schist. Retrogressed (and likely metasomatized) granulite.
major mineralogy: corundum, fuchsite, rutile.
(unpolarized light)

India corundum ruby in thin section

same as previous FKM-31 image (under crossed polars).

 




Karelia Russia fuchsite schist in thin section

sample: FKM-32a (taken from the same slab as FKM-32b)
locality: near Sosnovyy, Karelia Republic, Russia.
rock type: kyanite-staurolite-garnet-fuchsite schist. Amphibolite facies (kyanite zone) metamorphism of gradational metapelite and metaquartzite.
major mineralogy: Abundant porphyroblasts of almandine, chromian staurolite and kyanite in a matrix of chromian muscovite (“fuchsite”), sodic plagioclase (Ab88An12) and quartz, with subordinate Cr-Fe-bearing phlogopite, oxides (ilmenite and rutile [the 0.01 apfu Cr corresponds to ~4597 ppm Cr; also with ~806 ppm Fe]) and apatite.
(unpolarized light)

mineral representative mineral compositions in FKM-32a
rutile (Ti0.99Cr0.01)O2
ilmenite (Fe2+0.95Mn2+0.02Mg0.02)Ti1.01O3
fluorapatite (Ca4.97Mn2+0.01Na0.01)[P3.00O12](F0.93[OH]0.07)
almandine (Fe2+2.20Mg0.39Mn2+0.27Ca0.09Na0.01)(Al1.93Fe3+0.10Cr0.01)[Si2.96Al0.04O12]
kyanite (Al1.98Fe3+0.01Cr0.01)O[Si0.99Al0.01O4]
staurolite 4Al2O[Si0.98Al0.02O4] . (Al0.65Cr0.14Mg0.09Ti0.08Mn2+0.03V0.01)(Fe2+1.59Mg0.31Zn0.020.08)(O2.75[OH]1.25)
muscovite (K0.69Na0.23Ba0.010.07)(Al1.86Mg0.07FeT0.06Ti0.03Cr0.02V0.010.95)[Si3.04Al0.96O10]([OH]1.89O0.07F0.04)
phlogopite (K0.84Na0.050.11)(Mg1.56FeT0.87Al0.38Ti0.06Cr0.03V0.010.09)[Si2.73Al1.27O10]([OH]1.55F0.33O0.12)
“oligoclase” (Na0.88Ca0.15Sr0.01)[Si2.81Al1.19O8]

Karelia Russia fuchsite schist in thin section

same as previous FKM-32a image (under crossed polars).

 




Karelia Russia fuchsite schist in thin section

sample: FKM-32b (taken from the same slab as FKM-32a)
locality: near Sosnovyy, Karelia Republic, Russia.
rock type: fuchsite metaquartzite. Amphibolite facies metamorphism of gradational metapelite and metaquartzite.
major mineralogy: specimen acquired for fuchsite.
(unpolarized light)

Karelia Russia fuchsite schist in thin section

same as previous FKM-32b image (under crossed polars).

 




Jayville mine New York hastingsite in thin section

sample: FKM-33 (billet courtesy of C. Loehn, LSU)
locality: Jayville mine, St. Lawrence Co., NY, USA.
rock type: K-Fe metasomatite associated with Fe-oxide mineralization. The occurrence of metasomatic K-Cl-bearing hastingsite (sensu lato) with magnetite and apatite is characteristic of the ore zone in many IOCG (iron-oxide-Cu-Au) systems (Mazdab, 2003).
major mineralogy: Calcic amphibole is the dominant mineral in this thin section, verified by EPMA as K-F-Cl-bearing hastingsite. This amphibole is similar in composition, and of similar occurrence, to the potassic-magnesio-hastingsite in sample FKM-21. Some magnetite is present, as well as minor quartz and some biotite near Mg/(Mg+∑Fe) ≈ 0.5 and F/(OH+F) ≈ 0.5 in composition. Calcite present in the sample locally contains fine fibrous inclusions of a Fe-rich silicate which normalize best to greenalite, but alternatively could be pyrosmalite-(Fe) or another Fe-rich phyllosilicate.
(unpolarized light)

mineral representative mineral compositions in FKM-33
magnetite Fe2+1.00(Fe3+1.97Al0.01Fe2+0.01)O4
hastingsite (Na0.42K0.390.19)(Ca1.81Na0.19)(Fe2+2.63Mg1.19Fe3+1.01Al0.08Mn2+0.06Ti0.03Zn0.01)
[Si6.28Al1.71O22]([OH]1.07F0.62Cl0.26O0.06)
greenalite? (Ca0.07K0.01Na0.01)(FeT4.64Mg0.47Al0.12MnT0.110.66)[Si4.00O10]([OH]7.85Cl0.15)
fluorannite-rich
trioct mica ss
(K0.90Na0.050.05)(FeT1.43Mg1.33Al0.07Ti0.05MnT0.01Zn0.010.10)[Si2.91Al1.09O10](F0.94[OH]0.87O0.10Cl0.09)
annite-rich
trioct mica ss
(K0.90Na0.070.03)(FeT1.50Mg1.37Ti0.04Al0.01MnT0.01Zn0.010.06)[Si2.93Al1.07O10]([OH]0.92F0.90Cl0.10O0.08)

Jayville mine New York hastingsite in thin section

same as previous FKM-33 image (under crossed polars).

 




Nordfjord Norway eclogite in thin section

sample: FKM-34
locality: Nordfjord, Sogn og Fjordane, Norway.
rock type: garnet-omphacite eclogite. Eclogite facies metamorphosed mafic volcanic, likely Na-metasomatized (spillitization) prior to high-P metamorphism. Compare this to sample FKM-97, which is presumably also a garnet eclogite, but probably started out as a much different protolith.
major mineralogy: Classic mafic eclogite assemblage of predominately garnet (from Ca-Mg-rich almandine to Fe-Ca-rich pyrope) and slightly zoned omphacite. Minor kyanite, zoisite and paragonite, and rare barroisite to taramite NaCa-amphibole ss (more abundant in garnet) and magnesio-hornblende (more abundant in omphacite) are present. Accessory rutile (also with ~130 ppm Cr), fluorapatite to hydroxylapatite apatite ss, zircon, chalcopyrite and Co-pentlandite are also present.
(unpolarized light)

mineral representative mineral compositions in FKM-34
rutile (Ti0.99Fe3+0.01)O2
fluorapatite-rich apatite ss Ca4.97[P3.02O12](F0.65[OH]0.35)
hydroxylapatite-rich apatite ss (Ca4.94Na0.01)[P3.04O12]([OH]0.71F0.29)
almandine-rich garnet ss (Fe2+1.41Ca0.76Mg0.70Mn2+0.12Na0.01)(Al1.89Fe3+0.11)[Si3.00O12]
pyrope-rich garnet ss (most Ca-rich) (Mg1.15Fe2+1.09Ca0.70Mn2+0.05)(Al1.91Fe3+0.08)[Si3.00O12]
pyrope-rich garnet ss (most Mg-rich) (Mg1.39Fe2+1.09Ca0.49Mn2+0.02)(Al1.91Fe3+0.09)[Si3.00O12]
kyanite Al1.99O[Si0.99Al0.01O4]
zoisite Ca0.99Ca0.97Al1.02Al1.00(Al0.88Fe3+0.11)O[Si1.98Al0.02O7][Si0.99Al0.01O4](OH)
omphacite (main; most Na-Al-rich) (Ca0.63Na0.35Mg0.02)(Mg0.58Al0.35Fe2+0.03Fe3+0.03)[Si1.96Al0.04O6]
omphacite (patchy; most Ca-Mg-rich) (Ca0.76Na0.20Mg0.04)(Mg0.65Al0.27Fe2+0.08)[Si1.95Al0.05O6]
magnesio-hornblende (Na0.18K0.040.78)(Ca1.53Na0.47)(Mg3.88Al0.66Fe3+0.23Fe2+0.20Ti0.02Ni0.01)
[Si7.35Al0.65O22]([OH]1.94F0.03O0.03)
barroisite-rich NaCa-amph ss (Na0.26K0.050.69)(Ca1.38Na0.62)(Mg3.15Al0.90Fe3+0.69Fe2+0.21Ti0.04Mn2+0.01)
[Si6.72Al1.28O22]([OH]1.91O0.08F0.01)
barroisite (Hawthorne et al., 2012)
or ~[barroisite]-[taramite] join
(Leake et al., 1997) -rich NaCa-amph ss
(Na0.34K0.040.63)(Ca1.39Na0.61)(Mg3.02Al1.07Fe3+0.77Fe2+0.08Ti0.04Mn2+0.01)
[Si6.39Al1.61O22]([OH]1.89O0.08F0.02)
taramite-rich NaCa-amph ss (Na0.57K0.010.42)(Ca1.40Na0.60)(Mg1.76Al1.09Fe2+1.01Fe3+1.00Ti0.08Mn2+0.04Ni0.01)
[Si5.92Al2.08O22]([OH]1.83O0.16Cl0.01)
paragonite (Na0.91Ca0.04K0.010.04)(Al1.99FeT0.03Mg0.010.97)[Si2.93Al1.07O10]([OH]1.99O0.01)

Nordfjord Norway eclogite in thin section

same as previous FKM-34 image (under crossed polars).

 




nepheline sodalite syenite in thin section

sample: FKM-35
locality: unlabeled, but believed to be from the Bancroft area, Hastings Co., Ontario, Canada.
rock type: altered(?) nepheline-sodalite syenite, or possibly a nepheline-sodalite fenite?
major mineralogy: test.
(unpolarized light)

nepheline sodalite syenite in thin section

same as previous FKM-35 image (under crossed polars).

 




Franklin marble in thin section

sample: FKM-36
locality: unlabeled, but believed to be from the Franklin marble, in the general region of Sussex Co., NJ across to Orange Co., NY, USA.
rock type: spinel-chondrodite marble. Granulite facies meta-siliceous dolostone.
major mineralogy: Chondrodite with minor spinel in a coarse carbonate (calcite > dolomite). Sample FKM-8 is another chondrodite-bearing marble (also containing the additional humite group mineral norbergite) from the Franklin district. See the discussion under sample FKM-8 for details about the normalization scheme used for the humite group minerals and the rationale for estimating possible boron. Samples FKM-184, from a Franklin marble exposure in Edenville, NY, and FKM-112, also believed to be from the Franklin area, both contain yet another humite group species: clinohumite.
(unpolarized light)

mineral representative mineral compositions in FKM-36
spinel (analysis pending)
chondrodite (Mg3.88Fe3+0.08Fe3+0.02Ti0.01)[Si1.90B0.10O7.91(OH)0.09](F1.27[OH]0.73O0.01)

Franklin marble in thin section

same as previous FKM-36 image (under crossed polars).

 




Franklin marble with fluoborite in thin section

sample: FKM-37
locality: unlabeled, but believed to be from the Franklin marble, in the general region of Sussex Co., NJ across to Orange Co., NY, USA.
rock type: high grade borate-bearing marble. Granulite facies meta-siliceous dolostone (boron and fluorine may be of metasomatic origin?)
major mineralogy: specimen acquired for fluoborite.
(unpolarized light)

Franklin marble with fluoborite in thin section

same as previous FKM-37 image (under crossed polars).

 




Cascade Slide New York diopside marble xenolith in thin section

sample: FKM-38
locality: Cascade Slide, Cascade Mtn., Keene, Essex Co., NY, USA.
rock type: high grade diopside-bearing marble xenolith. Upper granulite facies metamorphosed siliceous limestone/dolostone.
major mineralogy: Abundant gemmy rounded diopside grains, with minor Al-bearing andradite and REE-bearing vesuvianite, in calcite. The vesuvianite was analyzed with the petroEPIDOTE analytical routine and normalized to 68[O] + 1[O] + 9[OH+F+Cl], with all Fe treated as Fe3+ and all Mn treated as Mn2+. The B values in the vesuvianite are an assumption and are not based on direct measurement; however, enough estimated B was added to each analysis so that the normalization would de-populate excess Si+Al from the nominally vacant B site. These additions also improved the overall analytical totals, and would be consistent with both the ability of vesuvianite to contain B, and the occurrence of harkerite in the assemblage. Scattered but tiny examples of an unknown Pb-Fe-Mn-Zn mineral (possibly a magnetoplumbite group mineral?; see below for a ∑cation = 26 normalization) and an unknown Ca-Fe-silicate (total = 90.2 wt%) occur in fractures and require further study. Tiny Fe sulfide (too small to analyze) is also present.
(unpolarized light)

mineral representative mineral compositions in FKM-38
unknown
(magnetoplumbite group?)
(Pb3.64Ca0.94Na0.26K0.20Sr0.01)∑5.05(Fe3+5.99Mn3+4.44Zn2.52Mn4+1.68Mg0.22Co0.13Ni0.01V0.01Zr0.01)∑15.01
[Si4.53Al1.30P0.07S0.01]∑5.91O38
calcite Ca0.99[CO3]
andradite (Ca2.96Mg0.01Fe2+0.01Mn2+0.01Y0.01)(Fe3+1.38Al0.57Ti0.03Mg0.02)[Si2.99Al0.01O12]
vesuvianite
(most REE-rich)
(Ca17.80Ce0.33La0.20Y0.09Nd0.05Mn2+0.05Pr0.02[HREE]0.02Na0.02Sr0.01Sm0.01Gd0.010.39)Al1.00O
(Al6.46Mg1.61Fe3+1.60Ti0.33)Mg2.00(B0.464.54)[Si2.00O7]4[Si0.984Al0.011S0.004P0.002O4]10([OH]7.10F1.70Cl0.19)
vesuvianite
(less REE-rich)
(Ca18.31Ce0.18La0.12Y0.04Mn2+0.04Nd0.02Pr0.01[HREE]0.01Na0.01Sr0.010.25)Al1.00O
(Al7.46Fe3+1.21Mg1.13Ti0.19)Mg2.00(B0.354.65)[Si2.00O7]4[Si0.987Al0.008S0.003P0.002O4]10([OH]7.09F1.74Cl0.17)
diopside Ca0.99(Mg0.88Fe3+0.05Al0.03Fe2+0.03)[Si1.91Al0.09O6]

Cascade Slide New York diopside marble xenolith in thin section

same as previous FKM-38 image (under crossed polars).

 




Russia charoite in thin section

sample: FKM-39 (separate specimen from sample FKM-39b)
locality: Murunskii massif, Chara River region, Sakha Republic, Russia.
rock type: Charoite schist; a K-rich metasomatite formed as part of a “charoitite-carbonatite” complex (Mitchell and Vladykin, 1996), this rock might be considered a type of K-fenite?
major mineralogy: Predominately charoite, zoned amphibole (cores of fluorian potassic-richterite grading outward to rims of fluorian potassic-magnesio-arfvedsonite), quartz, microcline, and minor aegirine (with up to 1140 ppm V). Sample FKM-39b is another charoite-bearing rock from the same general locality, although the charoite composition and the overall mineralogy differ slightly from this sample.
(unpolarized light)

Russia charoite in thin section

same as previous FKM-39 image (under crossed polars).

 




Russia charoite and tinaksite in thin section

sample: FKM-39b (separate specimen from sample FKM-39)
locality: Murunskii massif, Chara River region, Sakha Republic, Russia.
rock type: tinaksite-charoite-microcline schist; a K-rich metasomatite formed as part of a “charoitite-carbonatite” complex (Mitchell and Vladykin, 1996), this rock might be considered a type of K-fenite?
major mineralogy: Charoite, Fe-rich microcline and quartz are the dominant minerals in the sample, with additional abundant tinaksite blades and scattered V-bearing aegirine. Although conspicuous by optical microscopy, the aegirine is essentially indistinguishable from the charoite with BSE imaging due to similar average z. The microcline is zoned from 0.07 apfu Fe3+ in the core to 0.14 apfu Fe3+ in the rim. Although dispersion in microcline is generally reported as weak r > v, the microcline in this sample shows extreme v > r dispersion; indeed, the dispersion is so strong that under crossed polars the crystals show an atypical marked blue to brown anomalous birefringence. Another unusual feature of the microcline is that under the electron beam it shows an initial strong red cathodoluminescence that gradually becomes blue. As for the charoite, the normalization was done to ∑T = 70 (including Fe3+), based on the updated structural formula determined by Rozhdestvenskaya et al. in their 2010 [← subscription required] and 2011 papers. The 180[O] was reduced by sufficient [OH] to charge balance the formula, assigning all Fe as Fe3+ and assuming Mn3+/∑Mn = ~0.1; Mn3+ appears to be responsible for the lilac to violet color (Evdokimov et al., 2000; referenced in Rozhdestvenskaya et al., 2010). Additional H2O in the channels is estimated to give a yield a cumulative (all OH + H2O) charoite molar H2O content of ~16. Although this H2O estimate still leaves the analytical total a bit low (at ~98.8 wt%), the calculated H2O wt% is roughly 4.6 wt% which is consistent with the reported water values (one by DTA) referenced in the Handbook of Mineralogy’s charoite entry. The charoite is also strongly cathodoluminescent in blue. Minor minerals present include one spray of dalyite needles associated with some of the aegirine, abundant tiny wide-scattered inclusions of galena (particularly in the charoite), and some localized unidentified alteration of the charoite. Sample FKM-39 is another charoite-bearing rock from the same general locality, although the charoite composition and the overall mineralogy differ slightly from this sample.
(unpolarized light)

mineral representative mineral compositions in FKM-39b
tinaksite (K1.96Na0.01Sr0.01Ba0.01)(Na0.92Ca0.08)(Ca1.83Fe3+0.06Mg0.05Mn2+0.05V0.01)Ti1.01O1.00
[Si7.00O18]([OH]0.75O0.21F0.04)
aegirine (most Na+Fe-rich) (Na0.91Ca0.08)(Fe3+0.84Mg0.09Ti0.04Fe2+0.03)[Si2.00O6]
aegirine (most V-rich) (Na0.84Ca0.15Mg0.01)(Fe3+0.74Mg0.13V0.07Fe2+0.04Ti0.02)[Si1.99Fe3+0.01O6]
charoite (K14.59Ba1.35Sr0.53Mn2+~0.16)(Ca27.02Na4.64Sr0.25Zr0.04Mn3+~0.02Ti0.01)
[Si69.90Fe3+~0.04S0.04P0.02Al0.01O~174.21(OH)~5.79](F3.28[OH]0.70Cl0.02) . ~12.75H2O
dalyite (K1.84Ca0.13Fe2+0.02Ba0.01)(Zr0.77Ti0.21Hf~0.01Sn0.01)[Si5.91Ti0.06O14.99F0.01]
microcline (core) (K0.99Na0.01Mg0.01)[Si2.99Al0.94Fe3+0.07O8]
microcline (rim; most Fe-rich) (K0.99Mg0.01)[Si3.00Al0.85Fe3+0.14O8]

Russia charoite and tinaksite in thin section

same as previous FKM-39b image (under crossed polars).

 




Madagascar spinel and chlorapatite marble in thin section

sample: FKM-40
locality: Antanimora commune, Ambovombe district, Tuléar province, Madagascar.
rock type: high grade spinel-bearing marble, with a seemingly metasomatic contribution.
major mineralogy: Abundant spinel in calcite (relict dolomite is also present), with scattered patchy-zoned apatite ranging in composition from Cl-rich fluorapatite to essentially end-member chlorapatite. Minor quartz and small quantities of an ill-identified alteration phyllosilicate (possibly a Ca-dominant, Li-bearing tosudite; this normalizes extremely well) are present. One tiny, partially altered forsterite was also identified. Small thorianite inclusions are present in the apatite.
(unpolarized light)

mineral representative mineral compositions in FKM-40
spinel (Mg0.86Fe2+0.13)Al2.01O4
chlorapatite-rich
apatite ss
(Ca4.97La0.01Ce0.01)[P2.97Si0.03O12](Cl0.95F0.05)
fluorapatite-rich
apatite ss
(Ca4.96Sr0.01Ce0.01)[P2.98Si0.03O12](F0.70Cl0.25[OH]0.05)
“Ca-dominant tosudite”? (Ca0.33K0.04Na0.03Ba0.03)(Al4.27Mg0.97FeT0.41Zn0.01Li~0.34)[Si7.17Al0.82P0.01S0.01O18](OH)12 . 5H2O

Madagascar spinel and chlorapatite marble in thin section

same as previous FKM-40 image (under crossed polars).

 




Oka Quebec pyrochlore bearing carbonatite in thin section

sample: FKM-41
locality: Oka complex, Oka, Laurentides, Québec, Canada. This sample is similar to FKM-55, also from Oka, but is richer in silicates and pyrochlore.
rock type: carbonatite (sovite).
major mineralogy: Calcite, clinopyroxene, fluorcalciopyrochlore, fluorapatite, and minor phlogopite.
(unpolarized light)

Oka Quebec pyrochlore bearing carbonatite in thin section

same as previous FKM-41 image (under crossed polars).

 




Dora Maira Italy pyrope whiteschist in thin section

sample: FKM-42
locality: Martiniana Po, Dora Maira massif, Cuneo province, Piemonte, Italy.
rock type: pyrope-kyanite-talc schist (“whiteschist”). UHP eclogite facies sepiolitic(?) metapelite with accompanying metasomatism?
major mineralogy: Large shattered near end-member pyrope with quartz (presumably coesite at peak P), kyanite, minor rutile (also with ~1686-~2710 ppm Fe, ~204 ppm Cr and ~112 ppm Mn), phengitic white mica along the muscovite-aluminoceladonite join, and abundant talc. The garnets at this locality are notable, having so little Fe that they’re almost white in color, and growing to the size of a grapefruit (perhaps even larger!) Relict coesite may occur armored in some intact garnet (although not observed in this thin section). Small zircon and monazite crystals are scattered in the sample.
(unpolarized light)

mineral representative mineral compositions in FKM-42
rutile (Ti0.98Al0.01)O2
pyrope (Mg2.87Fe2+0.11Ca0.01Na0.01)(Al1.97Fe3+0.03)[Si2.95Al0.05O12]
kyanite Al2.00O[Si0.99Al0.01O4]
talc Na0.01(Mg2.87Al0.03FeT0.010.09)[Si4.03O10]([OH]1.89F0.10Cl0.01)
[muscovite]-[aluminoceladonite] join
(“phengite”)
(K0.78Na0.010.21)(Al1.51Mg0.53Ti0.010.95)[Si3.55Al0.45O10]([OH]1.91F0.06O0.03)

Dora Maira Italy pyrope whiteschist in thin section

same as previous FKM-42 image (under crossed polars).

 




Broken Hill tephroite marble in thin section

sample: FKM-43 (self-collected in June 1996)
locality: Pasminco North mine, Broken Hill, Yancowinna Co., NSW, Australia.
rock type: sphalerite-tephroite marble. Granulite facies Zn-Mn calcareous volcanogenic exhalite?
major mineralogy: Abundant tephroite and sphalerite, with minor galena, chalcopyrite and apatite, in calcite.
(unpolarized light)

mineral representative mineral compositions in FKM-43
galena Pb1.00S1.00
sphalerite (Zn0.76Fe2+0.16Mn2+0.07)S1.00
chalcopyrite Cu0.98Fe1.01S2.01
calcite (Ca0.95Mn2+0.05)[CO3]
fluorapatite (Ca4.99Mn2+0.02Y0.02)[P2.89Si0.05As5+0.01O12](F0.84[OH]0.15Cl0.01)
tephroite (Mn2+0.98Ca0.02)(Mn2+0.49Fe2+0.45Mg0.03Fe3+0.03)[Si0.97Fe3+0.03O4]

Broken Hill tephroite marble in thin section

same as previous FKM-43 image (under crossed polars).

 




Imilchil Morocco epidote titanite actinolite and chlorite in thin section

sample: FKM-44
locality: Imilchil, Er Rachidia province, Meknès-Tafilalet region, Morocco.
rock type: greenschist facies Ca-(Na) alteration assemblage associated with Fe-oxide mineralization. This is one of the typical hydrothermal mineral assemblages characteristic of IOCG (iron-oxide-Cu-Au) systems.
major mineralogy: epidote, titanite, actinolite, clinochlore. Data for the REE and trace element chemistry for the Imilchil titanite, as well a comparison to other IOCG-associated titanite, is given in Mazdab et al., 2008.
(unpolarized light)

Imilchil Morocco epidote titanite actinolite and chlorite in thin section

same as previous FKM-44 image (under crossed polars).

 




Franklin New Jersey hendricksite in thin section

sample: FKM-45 (billet from Univ. Arizona economic geology collection)
locality: Franklin mining district, Sussex Co., NJ, USA.
rock type: biotite-clinopyroxene-dominant calc-silicate rock. A skarn-like granulite facies Zn-Mn-rich volcanogenic exhalite(?), likely affected by subsequent metasomatism.
major mineralogy: Unlike most of the other Franklin area samples in this collection, this specimen is primarily massive silicate with subordinate oxide and little carbonate. Zn- and Mn-rich clinopyroxene, compositionally roughly along the diopside-augite nomenclature boundary (with respect to Ca content), is the dominant mineral present. This cpx consists of a slightly lower Z diopside making up the bulk of the material, and patchy areas of a slightly higher Z (due to increased Mn) augite scattered within. In the Franklin area, this fairly abundant Zn- and Mn-rich cpx is known as “jeffersonite” (see Frondel and Ito, 1966). Widespread in the cpx are small abundant inclusions of rhodonite, suggesting the cpx may have replaced it. Rhodonite also occurs as thicker bands, locally between cpx and mica. The mica was originally thought to be hendricksite, but analytical results indicate Mg>Zn, so it is in fact a Zn- and Mn-rich phlogopite. Minor amounts of two amphibole varieties are observed. An unusual Zn- and Mn-bearing hastingsite locally occurs between cpx and mica (similar in occurrence to the thicker rhodonite bands), and a comparably Zn- and Mn-enriched tremolite occurs as alteration stringers within the cpx. Franklinite and orange gahnite (as discrete grains, and as inclusions and overgrowths associated with the other; see FKM-48) are the dominant oxide minerals present, although a zincian pyrophanite also occurs as overgrowns on some of the franklinite. Scattered areas of Mn-bearing calcite occur throughout the sample, and as well as small inclusions within the cpx and rhodonite. Thin, enlongate stringers of willemite (bright green CL) occur in fractures in the gahnite and occasionally between the cleavages of the mica. Minor tiny ZnS (low-Fe but Cd-rich, by EDS; bright blue CL) and rare tiny galena are scattered in the sample.
(unpolarized light)

mineral representative mineral compositions in FKM-45
pyrophanite (Mn2+0.90Fe2+0.06Zn0.03Fe3+0.01)Ti0.99O3
gahnite (Zn0.89Fe2+0.08Mn2+0.02Mg0.01)(Al1.87Fe3+0.12)O4
franklinite (Zn0.80Mn2+0.19Mg0.01)(Fe3+1.52Al0.09Mn2+0.17Ti0.19Fe2+0.02)O4
calcite (Ca0.90Mn2+0.08Sr0.01)[CO3]
diopside-rich cpx ss
(“jeffersonite”; main)
(Ca0.84Na0.09Mn2+0.07)(Mg0.57Mn2+0.21Fe3+0.12Zn0.10)[Si1.95Al0.02Fe3+0.02O5.99F0.01]
augite-rich cpx ss
(“jeffersonite”; patchy)
(Ca0.79Mn2+0.13Na0.08)(Mg0.53Mn2+0.23Fe3+0.12Zn0.11Mn3+0.01)[Si1.93Al0.04Fe3+0.02O6]
rhodonite (coarse bands) (Ca0.89Mn2+0.11)Mn2+1.00Mn2+1.00Mn2+1.00(Zn0.37Mg0.26Mn2+0.25Mn3+0.08Fe3+0.03)[Si4.87Fe3+0.12O15]
rhodonite
(inclusions in cpx)
(Ca0.89Mn2+0.11)Mn2+1.00Mn2+1.00Mn2+1.00(Zn0.46Mg0.23Mn2+0.19Mn3+0.06Fe3+0.05)[Si4.87Fe3+0.12O15]
tremolite (Na0.18K0.020.80)(Ca1.27Na0.41Mn2+0.32)(Mg3.30Zn0.57Fe2+0.52Mn2+0.37Fe3+0.23)
[Si7.97Al0.03O22]([OH]1.83F0.16O0.01)
hastingsite (Na0.87K0.12)(Ca1.53Na0.35Mn2+0.11)(Mg2.49Mn2+0.79Zn0.68Fe3+0.62Fe2+0.25Al0.10Ti0.06)
[Si6.61Al1.38O22]([OH]1.35F0.52O0.12Cl0.01)
phlogopite (most Zn-rich) (K0.83Ba0.07Na0.050.05)(Mg1.72Zn0.58FeT0.31MnT0.27Ti0.050.07)[Si2.78Al1.22O10]([OH]1.51F0.39O0.09Cl0.01)

Franklin New Jersey hendricksite in thin section

same as previous FKM-45 image (under crossed polars).

 




Moose River New York prismatine gneiss in thin section

sample: FKM-46 (billet courtesy of J. Aleinikoff, U.S.G.S.-Denver; sample MR-99-12)
locality: Moose River, Lyonsdale, Lewis Co., NY, USA.
rock type: almandine-prismatine-cordierite gneiss. Granulite facies B-bearing metapelite.
major mineralogy: Porphyroblasts of prismatine, almandine(?) and cordierite (the latter partially altered to “pinite” [chlorite + muscovite]), with scattered biotite, tourmaline, minor rutile and minor hercynite, with quartz, K-feldspar and plagioclase. For comparison, other prismatine-bearing (and kornerupine-bearing) samples featured here include FKM-59 and FKM-67.
(unpolarized light)

Moose River New York prismatine gneiss in thin section

same as previous FKM-46 image (under crossed polars).

 




Franklin New Jersey willemite ore in thin section

sample: FKM-47
locality: Franklin mining district, Sussex Co., NJ, USA.
rock type: test.
major mineralogy: specimen acquired for willemite.
(unpolarized light)

Franklin New Jersey willemite ore in thin section

same as previous FKM-47 image (under crossed polars).

 

Franklin New Jersey willemite ore in thin section under UV light

same as previous FKM-47 images (under shortwave ultraviolet [SWUV] light).

 




Franklin New Jersey willemite ore in thin section

sample: FKM-48
locality: Franklin mining district, Sussex Co., NJ, USA.
rock type: gahnite-franklinite-tephroite-willemite marble. Granulite facies Zn-Mn calcareous volcanogenic exhalite?
major mineralogy: The specimen is a coarse-grained marble made up of Mn-rich calcite. The predominant porphyroblasts are willemite (the abundant colorless moderate relief crystals that slightly stand out from the calcite matrix), a Mg-rich Mn-olivine (the higher relief “highly-shattered” very pale gray crystals), franklinite (opaque) and gahnite* (pale to bright orange-yellow; see FKM-45). Within some of the gahnite is minor Ca-rich rhodochrosite, and some of the gahnite also shows overgrowths of franklinite. Scattered tiny barite (too small to accurately analyze) is also present. The Mg-Mn-olivine has overall Mn>Mg and so is ostensibly tephroite. However, site occupancy measurements on Mg-Mn-olivine by Francis and Ribbe, 1980 (including on a Zn-bearing Franklin sample similar to the one presented here) demonstrate significant ordering of Mn2+ into the slightly larger M2 site. Hence, with Mg predicted to be more abundant than Mn in the M1 site in this sample, it is likely this olivine more closely resembles an ordered M2MnM1Mg[SiO4] hypothetical end-member than a disordered Mg-bearing tephroite, M2(Mn,Mg)M1(Mn,Mg)[SiO4].
 
*Note: prior to examining this thin section on the microprobe, the yellow gahnite in this sample was originally thought to be andradite garnet, and is misidentified as such in Isotropic Minerals in Thin Section; I regret the error, and offer a correction here. Because only a limited number of optical tests are available to characterize isotropic minerals in thin section (i.e. color, relief [relative refractive index], cleavage [if present], habit and paragenesis], these minerals can in some cases be the among the most challenging to differentiate.
(unpolarized light)

mineral representative mineral compositions in FKM-48
gahnite (most Fe-rich) (Zn0.90Fe2+0.04Mn2+0.04Mg0.02)(Al1.76Fe3+0.24)O4
gahnite (most Al-rich) (Zn0.92Fe2+0.06Mn2+0.01Mg0.01)(Al1.91Fe3+0.09)O4
franklinite (Zn0.80Mn2+0.13Mg0.04Fe2+0.03)(Fe3+1.56Al0.18Mn2+0.13Ti0.13)O4
calcite (bulk) (Ca0.85Mn2+0.12Mg0.02Sr0.01)[CO3]
rhodochrosite (inclusions in gahnite) (Mn2+0.81Ca0.18Mg0.01)[CO3]
willemite (Zn0.67Mn2+0.17Mg0.15)Zn0.99[Si1.00O4]
“MnMg[SiO4]” olivine (historically tephroite) Mn2+1.00(Mg0.61Zn0.22Mn2+0.15Mn3+0.03)[Si0.97Fe3+0.03O4]

Franklin New Jersey willemite ore in thin section

same as previous FKM-48 image (under crossed polars).

 

Franklin New Jersey willemite ore in thin section under UV light

same as previous FKM-48 images (under shortwave ultraviolet [SWUV] light).

 




Mexico nepheline syenite in thin section

sample: FKM-49 (billet from Univ. Arizona economic geology collection, J. Hamblock thesis collection)
locality: San Carlos intrusive complex, Tamaulipas, Mexico.
rock type: nepheline syenite.
major mineralogy: Amphibole (ferri-kaersutite grading to and/or overgrown with magnesio-hastingsite), scattered large titanite crystals (to ~1 cm, in the hand sample), nepheline, orthoclase, and plagioclase.
(unpolarized light)

Mexico nepheline syenite in thin section

same as previous FKM-49 image (under crossed polars).

 




Lovozero Kola Russia murmanite and aegirine in thin section

sample: FKM-50
locality: Lovozero massif, Kola Peninsula, Murmanskaja Oblast’, Russia.
rock type: test.
major mineralogy: specimen acquired for murmanite.
(unpolarized light)

Lovozero Kola Russia murmanite and aegirine in thin section

same as previous FKM-50 image (under crossed polars).

 




Lovozero Kola Russia lorenzenite in thin section

sample: FKM-51
locality: Lovozero massif, Kola Peninsula, Murmanskaja Oblast’, Russia.
rock type: test.
major mineralogy: specimen acquired for lorenzenite.
(unpolarized light)

Lovozero Kola Russia lorenzenite in thin section

same as previous FKM-51 image (under crossed polars).

 




Dara-i-Pioz Tajikistan reedmergnerite alkali granite in thin section

sample: FKM-52
locality: Darai-Pioz glacier, Alai range, Tien Shan Mtns., Tajikistan.
rock type: highly-evolved B-rich alkali granite.
major mineralogy: Almost entirely coarse reedmergnerite, intermixed with veinlet-like fine-grained quartz and very minor lepidolite. Sparse stillwellite-(Ce) adjacent to a chain of sparse purple manganoeudialyte(?), the latter with a tiny inclusion of sazykinaite-(Y) adjacent to a tiny inclusion of zeravshanite.
(unpolarized light)

Dara-i-Pioz Tajikistan reedmergnerite alkali granite in thin section

same as previous FKM-52 image (under crossed polars).

 




Tres Pozos Mexico gillespite and cherchiaraite in thin section

sample: FKM-53 (billet courtesy of M. Origlieri, Univ. Arizona; separate specimen from sample FKM-53b)
locality: Madrelena mine, Tres Pozos, Baja California Norte, Mexico.
rock type: test.
major mineralogy: specimen acquired for gillespite. Also contains sanbornite, titantaramellite, quartz, bazirite, cherchiaraite-(Fe), alforsite, and at least one additional unidentified Ba-Ti-Si-Cl mineral.
(unpolarized light)

Tres Pozos Mexico gillespite and cherchiaraite in thin section

same as previous FKM-53 image (under crossed polars).

 




Tres Pozos Mexico gillespite and cherchiaraite in thin section

sample: FKM-53b (separate specimen from sample FKM-53)
locality: Madrelena mine, Tres Pozos, Baja California Norte, Mexico.
rock type: test.
major mineralogy: specimen acquired for gillespite.
(unpolarized light)

Tres Pozos Mexico gillespite and cherchiaraite in thin section

same as previous FKM-53b image (under crossed polars).

 




Franklin New Jersey rhodonite and jeffersonite in thin section

sample: FKM-54
locality: Franklin mining district, Sussex Co., NJ, USA.
rock type: test.
major mineralogy: rhodonite, andradite, franklinite, cpx (“jeffersonite”).
(unpolarized light)

Franklin New Jersey rhodonite and jeffersonite in thin section

same as previous FKM-54 image (under crossed polars).

 




Oka Quebec pyrochlore bearing carbonatite in thin section

sample: FKM-55 (billet from Univ. Arizona economic geology collection; sample 96-15a).
locality: Oka complex, Oka, Laurentides, Québec, Canada.
rock type: carbonatite (sovite).
major mineralogy: calcite, pyrochlore, phologopite, diopside, apatite. This sample is similar to FKM-41, also from Oka, but is poorer in silicates and pyrochlore.
(unpolarized light)

Oka Quebec pyrochlore bearing carbonatite in thin section

same as previous FKM-55 image (under crossed polars).

 




Oka Quebec hauyne and melilite okaite in thin section

sample: FKM-56 (billet from Univ. Arizona economic geology collection; sample 96-13)
locality: Oka complex, Oka, Laurentides, Québec, Canada.
rock type: “okaite”. Intrusive equivalent of haüyne melilitite.
major mineralogy: Haüyne, melilite, britholite.
(unpolarized light)

Oka Quebec hauyne and melilite okaite in thin section

same as previous FKM-56 image (under crossed polars).

 




Oka Quebec niocalite bearing carbonatite in thin section

sample: FKM-57 (billet from Univ. Arizona economic geology collection; sample 96-6)
locality: Oka complex, Oka, Laurentides, Québec, Canada.
rock type: carbonatite (sovite).
major mineralogy: Niocalite.
(unpolarized light)

Oka Quebec niocalite bearing carbonatite in thin section

same as previous FKM-57 image (under crossed polars).

 




Meldon mine malayaite-bearing skarn in thin section

sample: FKM-58
locality: Meldon mine, Okehampton, Devon, England, UK.
rock type: test.
major mineralogy: Malayaite.
(unpolarized light)

Meldon mine malayaite-bearing skarn in thin section

same as previous FKM-58 image (under crossed polars).

 




Waldheim Germany prismatine gneiss in thin section

sample: FKM-59
locality: Waldheim, Döbeln, Saxony, Germany.
rock type: granulite.
major mineralogy: Prismatine, dravite. For comparison, other prismatine-bearing (and kornerupine-bearing) samples featured here include FKM-46 and FKM-67.
(unpolarized light)

Waldheim Germany prismatine gneiss in thin section

same as previous FKM-59 image (under crossed polars).

 




Umbozero mine Lovozero Kola Russia ussingite and serandite syenite in thin section

sample: FKM-60
locality: Umbozero mine, Alluaiv Mtn., Lovozero massif, Kola Peninsula, Murmanskaja Oblast’, Russia.
rock type: test.
major mineralogy: Ussingite, sérandite.
(unpolarized light)

Umbozero mine Lovozero Kola Russia ussingite and serandite syenite in thin section

same as previous FKM-60 image (under crossed polars).

 




Canta Peru dumortierite in thin section

sample: FKM-61
locality: Canta province, Lima Department, Peru.
rock type: test. Compare this sample to the similar boron-bearing advanced argillic alteration assemblage in samples FKM-70 and FKM-187.
major mineralogy: Dumortierite.
(unpolarized light)

Canta Peru dumortierite in thin section

same as previous FKM-61 image (under crossed polars).

 




Khibiny Kola Russia syenite in thin section

sample: FKM-62
locality: Khibiny massif, Kola Peninsula, Murmanskaja Oblast’, Russia.
rock type: test.
major mineralogy: specimen acquired for eudialyte.
(unpolarized light)

Khibiny Kola Russia syenite in thin section

same as previous FKM-62 image (under crossed polars).

 




Tanzania spinel and pargasite marble in thin section

sample: FKM-63
locality: Mahenge, Morogoro region, Tanzania.
rock type: high grade spinel-bearing marble.
major mineralogy: Spinel (in the hand sample, but not in this thin section), along with pargasite, phlogopite and minor Cl-bearing fluorapatite, in a calcite + dolomite marble.
(unpolarized light)

mineral representative mineral compositions in FKM-63
fluorapatite (most Cl-rich) Ca4.99[P3.01O12](F0.61[OH]0.24Cl0.15)
pargasite (Na0.60K0.12Ca0.040.24)Ca2.00(Mg4.02Al0.77Ti0.14Fe3+0.04V0.02)[Si6.09Al1.91O22]([OH]1.27F0.42O0.29Cl0.02)
phlogopite (K0.90Na0.05Ba0.010.04)(Mg2.82Al0.14FeT0.01Ti0.010.02)[Si2.90Al1.10O10]([OH]1.58F0.39O0.02Cl0.01)
clinochlore (Mg4.58Al1.29FeT0.03Ti0.010.09)[Si2.88Al1.12O10]([OH]7.90F0.09O0.01)

Tanzania spinel and pargasite marble in thin section

same as previous FKM-63 image (under crossed polars).

 




Kipawa Canada miserite and agrellite in thin section

sample: FKM-64
locality: Kipawa alkaline complex, Les Lacs-du-Témiscamingue, Abitibi-Témiscamingue, Québec, Canada.
rock type: metamorphosed alkali syenite.
major mineralogy: Miserite, agrellite (with rims of REE-bearing pectolite).
(unpolarized light)

Kipawa Canada miserite and agrellite in thin section

same as previous FKM-64 image (under crossed polars).

 




Kipawa Canada mosandrite and eudialyte in thin section

sample: FKM-65
locality: Kipawa alkaline complex, Les Lacs-du-Témiscamingue, Abitibi-Témiscamingue, Québec, Canada.
rock type: metamorphosed alkali syenite.
major mineralogy: Mosandrite, eudialyte, fluoro-richterite, microcline. Sample FKM-27, also from the Kipawa complex, is similar to this sample but lacks any significant mosandrite.
(unpolarized light)

Kipawa Canada mosandrite and eudialyte in thin section

same as previous FKM-65 image (under crossed polars).

 




Cerro Sapo Bolivia sodalite ankerite burbankite carbonatite in thin section

sample: FKM-66
locality: Cerro Sapo, Ayopaya province, Cochabamba Department, Bolivia.
rock type: ankerite-sodalite carbonatite.
major mineralogy: Primarily massive sodalite with abundant coarse subhedral crystals of a dolomite-group carbonate. The cores of the carbonate are a vuggy (former solid or fluid inclusions?) Fe-rich dolomite grading outwards to a clean Mg-rich ankerite. The sodalite is locally altered to small patches of analcime. The 2nd order blue birefringence mica-like blade in the NE corner of the XP image was on first inspection thought to be phlogopite, but was subsequently found to be B(-) with a 2V° ≈ 80°; this material was verified by EPMA to be the Na-Al-carbonate dawsonite (for elements z ≥ 9, only Na and Al were present, but a good quantitative analysis was not possible due to the mineral’s extreme instability under the electron beam, even using a 10 μm defocused beam and slow raster). Note that dawsonite’s actual maximum birefringence is δ = 0.130 (so ~7th to ~8th order!), but this grain is fortuitously oriented to give an almost perfectly centered optic axis figure. The main dawsonite mass encloses small blades of orthoclase (these are also sparsely scattered elsewhere in the sample), as well as a zeolite that appears to be a Sr-dominant end-member of edingtonite (based on the Al:Si ratio and estimated H2O content). Small but abundant grains of REE-rich burbankite, Th-rich ancylite-(Ce) and Ca-rich strontianite are widely scattered within the sample, and in some cases are intergrown together. EPMA analyses of both REE-bearing carbonates gave high totals (~106 wt%) but acceptable stoichiometries and charge balances. A single small mass of REE-bearing goyazite was also observed.
(unpolarized light)

mineral representative mineral compositions in FKM-66
dolomite-rich dolomite group ss
(vuggy interior)
(Ca0.97Mn2+0.03)(Mg0.64Fe2+0.34Mn2+0.02)[CO3]2
ankerite-rich dolomite group ss
(clean exterior)
(Ca0.98Na0.01Mn2+0.01)(Fe2+0.60Mg0.37Mn2+0.04)[CO3]2
strontianite (Sr0.77Ca0.17Ba0.02Ce0.01La0.01Na0.01)[(CO3)0.99(CO3F)0.01]
burbankite (Na2.27Ca0.66Sr0.07)(Sr2.20Ce0.26La0.15Ba0.12Nd0.10Th0.08Pr0.03Sm0.03Gd0.03)
[(CO3)4.96(CO3F)0.04]
ancylite-(Ce) (Ce0.37La0.19Th0.18Nd0.13Pr0.04Sm0.03Gd0.02Ba0.01Sr0.03)(Sr0.84Ca0.17)
[CO3]2([OH]0.90F0.10) . ~1H2O
goyazite (Sr0.58Ba0.28Ca0.10Ce0.02La0.01Nd0.01Na0.01)(Al2.99Fe3+0.01)
[P0.99Si0.01O3.02(OH)0.98][P1.00O4]([OH]5.91F0.09)
orthoclase (K0.98Na0.02)[Si2.98Al1.02O8]
sodalite Na5.92[Si5.92Al6.08O24] . Na2.01(Cl1.97[CO3]0.02)
“Sr-edingtonite?” (Sr0.38Ca0.29Ba0.22K0.07Na0.07)[Si2.96Al2.04O10] . ~4H2O
analcime Na0.94[Si1.97Al1.03O6] . H2O

Cerro Sapo Bolivia sodalite ankerite burbankite carbonatite in thin section

same as previous FKM-66 image (under crossed polars).

 




Australia kornerupine gneiss in thin section

sample: FKM-67
locality: Plenty River mine area, Harts Range, NT, Australia. This material is ostensibly identical to that found at the classic Mt. Riddock station locality, but it’s unclear if the Plenty River mine area is a distinct occurrence in the Harts Range, or simply an imprecise reference to the Mt. Riddock locality.
rock type: test.
major mineralogy: test. For comparison, other prismatine-bearing (and kornerupine-bearing) samples featured here include FKM-46 and FKM-59.
(unpolarized light)

Australia kornerupine gneiss in thin section

same as previous FKM-67 image (under crossed polars).

 




Longido Tanzania corundum ruby zoisite and tschermakite in thin section

sample: FKM-68
locality: Muriatata Hills, Longido, Mt. Kilimanjaro region, Tanzania.
rock type: corundum-zoisite-pargasite gneiss. Presumably a higher pressure (eclogite facies) equivalent of corundum-bearing amphibolite (i.e., akin to sample FKM-24); estimated at between 700°-850° C and between ~10-20 kbars, according to experimental phase relations. Note that unlike FKM-24, the amphibole in this sample is pargasite rather than tschermakite.
major mineralogy: Porphyroblasts of pale red Cr-bearing corundum (“ruby”) in a matrix of coarse zoisite and pargasite. Inclusions of remnant(?) Cr- and Fe3+-enriched spinel and pumpellyite-(Al) occur, primarily within the zoisite. Minor retrograde alteration (corundum veined by diaspore and chlorite along zoisite-amphibole boundaries) is also present.
(unpolarized light)

mineral representative mineral compositions in FKM-68
spinel (Mg0.62Fe2+0.35Mn2+0.01Zn0.01)(Al1.76Cr0.23Fe3+0.01)O4
corundum (Al1.99Cr0.01)O3
diaspore (Al0.99Cr0.01)O(OH)
zoisite Ca1.00(Ca0.98Sr0.02)Al1.01Al1.00(Al0.94Fe3+0.05Cr0.01)O[Si1.97Al0.03O7][Si0.98Al0.02O4](OH)
pumpellyite-(Al) (Ca1.96Na0.02Fe2+0.01Mn2+0.01)(Al0.63Mg0.32FeT0.05)Al2.00
[Si1.98Al0.02O7][Si0.99Al0.01O4]([OH]~1.36O~0.64) . H2O
pargasite (most Cr-rich) (Na0.52K0.110.37)(Ca1.97Na0.03)(Mg3.23Al1.07Fe3+0.29Fe2+0.26Cr0.11Ti0.02Mn2+0.01Ni0.01)
[Si5.91Al2.08O22]([OH]1.96O0.04)
clinochlore (Ca0.01K0.01)(Mg3.96Al1.23FeT0.54Cr0.09MnT0.01Ni0.010.16)[Si2.81Al1.19O10](OH)8.00

Longido Tanzania corundum ruby zoisite and tschermakite in thin section

same as previous FKM-68 image (under crossed polars).

 




Mautia Hill Tanzania yoderite whiteschist in thin section

sample: FKM-69 (separate specimen from sample FKM-69b)
locality: Mautia Hill, Kongwa, Kongwa district, Dodoma region, Tanzania.
rock type: yoderite-kyanite-talc metaquartzite (“whiteschist”). UHP eclogite facies sepiolitic(?) metapelite with accompanying metasomatism?
major mineralogy: Yoderite overgrowing orange kyanite, in a matrix of talc and dominant quartz. Scattered hematite, with some associated rutile (the 0.04 apfu Mn corresponds to ~25800 ppm Mn; also with ~102 ppm Cr), is also present.
(unpolarized light)

mineral representative mineral compositions in FKM-69
rutile (Ti0.94Mn4+?0.04Fe3+0.01)O2
hematite (Fe3+1.90Mn3+0.06Al0.01Ti0.01Mg0.01)O3
kyanite (Al1.97Fe3+0.03)O[Si0.98Al0.02O4]
yoderite (Mg1.90Fe2+0.05Mn2+0.05)(Al5.57Fe3+0.39Mg0.03Ti0.01)O2[Si0.99Al0.01O4]4(OH)2.00
talc Ca0.01(Mg2.75Al0.17FeT0.020.06)[Si3.91Al0.09O10]([OH]1.98F0.02)

Mautia Hill Tanzania yoderite whiteschist in thin section

same as previous FKM-69 image (under crossed polars).

 




Mautia Hill Tanzania yoderite whiteschist in thin section

sample: FKM-69b (separate specimen from sample FKM-69)
locality: Mautia Hill, Kongwa, Kongwa district, Dodoma region, Tanzania.
rock type: yoderite-kyanite-talc metaquartzite (“whiteschist”). UHP eclogite facies sepiolitic(?) metapelite with accompanying metasomatism?
major mineralogy: Yoderite overgrowing orange kyanite, in a matrix of talc and dominant quartz.
(unpolarized light)

Mautia Hill Tanzania yoderite whiteschist in thin section

same as previous FKM-69b image (under crossed polars).

 




Japan dumortierite and foitite advanced argillic alteration assemblage in thin section

sample: FKM-70
locality: Tsukigata mine, Koriyama, Fukushima Prefecture, Honshu Island, Japan.
rock type: test. Compare this sample to the similar boron-bearing advanced argillic alteration assemblage in sample FKM-61 and FKM-187.
major mineralogy: Dumortierite, foitite.
(unpolarized light)

Japan dumortierite and foitite advanced argillic alteration assemblage in thin section

same as previous FKM-70 image (under crossed polars).

 




Alto Chapare Bolivia povondraite in thin section

sample: FKM-71
locality: Alto Chapare district, Chapare province, Cochabamba Department, Bolivia.
rock type: test.
major mineralogy: Abundant large zoned tourmaline ranging from dominant povondraite to alumino-povondraite, with small patches of a new tourmaline (“K-povondraite”). Additional crystals of a notably lower-Fe oxy-dravite are scattered in the matrix of hydromagnesite, K-feldspar, hematite and minor talc. Reported M3+/∑M (where M = Fe+Mn) and O/(O+OH) in the tourmaline analyses are estimations and have not been independently measured. For the povondraite-related tourmalines, values of M3+/∑M between 0.708 and 0.825 normalize to un-named tourmaline end-members inconsistent with their very high Fe contents (i.e. oxygen apfu in the “W” site becomes less than 0.50); for values of M3+/∑M < 0.708, the normalizations fail altogether (oxygen apfu in the “W” site calculates to less than zero). For the oxy-dravite only, values of M3+/∑M < 0.12 normalize to dravite instead of oxy-dravite; although mathematically permissible, this would again seem to be inconsistent with the overall highly-oxidized assemblage present in the sample.
(unpolarized light)

mineral representative mineral compositions in FKM-71
oxy-dravite (in matrix) (Na0.91K0.060.06)(Al1.93Mg0.55Fe2+0.49Ti0.03)(Al4.45Mg1.00Fe3+0.55)
[Si5.97Al0.02P0.01O18](BO3)3(OH)3(O0.92F0.08)
alumino-povondraite-rich tourmaline ss (Na0.80K0.20)Fe3+3.00(Al2.24Mg2.13Fe3+1.01Ti0.28Fe2+0.24V0.01)
[Si6.09O18](BO3)3(OH)3O1.00
povondraite-rich tourmaline ss (Na0.64K0.37Ca0.06)Fe3+3.00(Fe3+3.05Mg1.69Fe2+0.58Al0.55Ti0.03V0.01)
[Si6.10O18](BO3)3(OH)3O1.00
“K-povondraite”-rich tourmaline ss (K0.58Na0.45)Fe3+3.00(Fe3+3.82Mg1.82Fe2+0.30Al0.01Ti0.01V0.01)
[Si5.96P0.06O18](BO3)3(OH)3O1.00

Alto Chapare Bolivia povondraite in thin section

same as previous FKM-71 image (under crossed polars).

 




Klause Austria kolbeckite-bearing latite in thin section

sample: FKM-72
locality: Schlarbaum quarry, Klause, Bad Gleichenberg, Styria, Austria.
rock type: altered latite.
major mineralogy: Kolbeckite present in the hand sample, but not observed in this thin section; plagioclase phenocrysts in a volcanic matrix.
(unpolarized light)

Klause Austria kolbeckite-bearing latite in thin section

same as previous FKM-72 image (under crossed polars).

 




Langesundfjord Norway hiortdahlite syenite in thin section

sample: FKM-73
locality: Stokkøya, Langesundfjorden, Larvik, Vestfold, Norway.
rock type: nepheline syenite.
major mineralogy: specimen acquired for hiortdahlite.
(unpolarized light)

Langesundfjord Norway hiortdahlite syenite in thin section

same as previous FKM-73 image (under crossed polars).

 




Palabora South Africa carbonatite in thin section

sample: FKM-74 (billet from Univ. Arizona economic geology collection; sample PAL-3)
locality: Palabora mine, Loolekop, Phalaborwa, Limpopo province, South Africa.
rock type: K-rich fenite associated with a carbonatite.
major mineralogy: microcline, arfvedsonite, aegirine, apatite (notably as large crystals in a calcite vein surface, in the hand sample).
(unpolarized light)

Palabora South Africa carbonatite in thin section

same as previous FKM-74 image (under crossed polars).

 




Chongwe River Zambia staurolite lusakite and cobalt-bearing hogbomite in thin section

sample: FKM-75 (billet courtesy of S. Vrána, Czech Geologic Survey)
locality: Chongwe River region (~120 km E. of Lusaka), Zambia.
rock type: staurolite-kyanite-magnetite gneiss. Amphibolite facies “ferrolite” (due to this rock’s unusual bulk composition, its protolith has not been definitively ascertained).
major mineralogy: Abundant blue(!) Co-bearing staurolite (“lusakite”), associated with and sometimes overgrowing abundant kyanite, with minor sillimanite, all hosted by intergrown magnetite, hematite, ilmenite, and quartz. Tiny violet “cobaltohögbomite-2N2S“, a potentially new member of the högbomite family, is abundantly scattered within the oxide. Minor phyllosilicate alteration consists of both margarite and a more abundant cobaltoan clinochlore. The sample is poor in sulfides, with only a few scattered grains of cobalt-pentlandite and linnaeite. Note that the site fillings in the staurolite and “cobaltohögbomite-2N2S” are estimated and have not be verified by crystal structure analyses. Similarly, M3+/∑M ratio and OH content of the staurolite are also estimated, while the polysome of the högbomite species is based off of the reported polysome for cobaltoan ferrohögbomite-2N2S from the same locality (see the mindat.org ferrohögbomite-2N2S entry). Scattered rutile (also with ~196 ppm Co and ~150 ppm Mn) is also present.
(unpolarized light)

mineral representative mineral compositions in FKM-75
cobalt-pentlandite (Co7.93Ni0.97Fe0.10)S8
linnaeite (Co2+0.68Ni2+0.32)(Co3+1.97Fe3+0.03)S4
rutile (Ti0.99Fe3+0.01)O2
hematite (Fe3+0.81Fe2+0.14Co0.05)(Fe3+0.79Ti0.19V0.02)O3
ilmenite (Fe2+0.82Co0.06Fe3+0.05Mg0.04Mn2+0.02)(Ti0.95Fe3+0.05)O3
magnetite (Fe2+0.93Co0.06Ni0.01)(Fe3+1.99Al0.01)O4
“cobaltohögbomite-2N2S (Al0.55Fe2+0.44)(Al3.54Ti0.45Ga0.01)O7([OH]0.94F0.06) .
(Co0.88Mg0.72Fe2+0.29Ni0.07Zn0.03Mn2+0.01)(Al3.23Fe3+0.77)O8
sillimanite (Al1.97Fe3+0.02)O[Si0.97Al0.03O4]
kyanite (Al1.99Fe3+0.01)O[Si0.99Al0.01O4]
staurolite 4Al2O[Si0.97Al0.03O4] .
(Al0.84Mg0.10Ti0.05Mn2+0.01)(Fe2+1.08Mg0.51Co0.38Ni0.02Zn0.01)(O2.80[OH]1.16F0.04)
margarite (Ca0.70Na0.280.02)(Al1.97FeT0.06Mg0.05Co0.010.91)[Si2.12Al1.88O10](OH)2.00
clinochlore (Mg3.51Al1.37FeT0.80Co0.19Ni0.050.08)[Si2.62Al1.38O10]([OH]7.98F0.02)

Chongwe River Zambia staurolite lusakite and cobalt-bearing hogbomite in thin section

same as previous FKM-75 image (under crossed polars).

 




Broken Hill inesite in thin section

sample: FKM-76
locality: Broken Hill, Yancowinna Co., NSW, Australia.
rock type: test.
major mineralogy: inesite.
(unpolarized light)

Broken Hill inesite in thin section

same as previous FKM-76 image (under crossed polars).

 




Ilimaussaq Greenland eudialyte kakortokite in thin section

sample: FKM-77
locality: Ilímaussaq complex, Narsaq, Kujalleq, Greenland.
rock type: kakortokite. Cumulate eudialyte-nepheline syenite.
major mineralogy: Eudialyte, arfvedsonite, nepheline, plagioclase.
(unpolarized light)

Ilimaussaq Greenland eudialyte kakortokite in thin section

same as previous FKM-77 image (under crossed polars).

 




Bozeman mine Montana corundum gneiss in thin section

sample: FKM-78
locality: Bozeman Corundum Company mine, Gallatin Gateway, Gallatin Co., MT, USA.
rock type: test.
major mineralogy: corundum.
(unpolarized light)

Bozeman mine Montana corundum gneiss in thin section

same as previous FKM-78 image (under crossed polars).

 




Leucite Hills Wyoming leucitite in thin section

sample: FKM-79
locality: Black Rock, Leucite Hills, Sweetwater Co., WY, USA.
rock type: test.
major mineralogy: specimen acquired for fluoro-potassic-richterite, but no amphibole is present in this thin section.
(unpolarized light)

Leucite Hills Wyoming leucitite in thin section

same as previous FKM-79 image (under crossed polars).

 




Eifel Germany hauyne phonolite in thin section

sample: FKM-80
locality: In den Dellen quarry, Niedermendig, Mendig, Laacher See volcanic complex, Eifel, Rhineland-Palatinate, Germany.
rock type: haüyne phonolite.
major mineralogy: Largely sanidine, with scattered haüyne (sparse in this particular thin section and not easily visible in these images), and minor apatite, aegirine, and oxide.
(unpolarized light)

Eifel Germany hauyne phonolite in thin section

same as previous FKM-80 image (under crossed polars).

 




Wippertal Germany carpholite in thin section

sample: FKM-81
locality: Biesenrode, Wippra metamorphic zone (Wippertal), Harz, Saxony-Anhalt, Germany.
rock type: quartz-carpholite schist. Low-T blueschist facies of original presumably siliceous manganiferous sediment.
major mineralogy: Bands of subparallel carpholite fibers (with local small patches of magnesiocarpholite) intergrown with quartz, minor chlorite (sudoite) and Fe-oxide. Scattered tiny apatite is also present (containing ~450-850 ppm As).
(unpolarized light)

mineral representative mineral compositions in FKM-81
fluorapatite (Ca4.87Mn2+0.07[M+HREE]0.01)[P3.02Si0.01O12](F0.96[OH]0.04)
carpholite-rich ss (main) (Mn2+0.56Mg0.29Fe2+0.13Fe3+0.01Ti0.01)(Al1.99Fe3+0.01)[Si1.97Al0.03O6]([OH]3.95F0.05)
magnesiocarpholite-rich ss
(sparse patches in main)
(Mg0.48Mn2+0.35Fe2+0.15)Al2.00[Si1.98Al0.02O6]([OH]3.94F0.06)
sudoite (Al2.88Mg1.70FeT0.31MnT0.03Ni0.011.07)[Si3.15Al0.85O10]([OH]7.99F0.01)

Wippertal Germany carpholite in thin section

same as previous FKM-81 image (under crossed polars).

 




Madagascar dumortierite in thin section

sample: FKM-82
locality: Itremo commune, Ambatofinandrahana district, Fianarantsoa province, Madagascar.
rock type: test.
major mineralogy: specimen acquired for dumortierite and sillimanite.
(unpolarized light)

Madagascar dumortierite in thin section

same as previous FKM-82 image (under crossed polars).

 




Langban Sweden magnesioferrite in thin section

sample: FKM-83
locality: Långban, Filipstad, Värmland, Sweden.
rock type: test.
major mineralogy: specimen acquired for magnesioferrite.
(unpolarized light)

Langban Sweden magnesioferrite in thin section

same as previous FKM-83 image (under crossed polars).

 




Burma kosmochlor and eckermannite jadeitite in thin section

sample: FKM-84
locality: ~3 km SW of Kansi, Hpakant-Tawmaw jade tract, Kachin state, Burma.
rock type: altered jadeitite vein in eckermannite schist. Blueschist facies Na-metasomatite(?)
major mineralogy: The vein envelope portion (upper third of image) is largely Cr-bearing eckermannite, moderately veined with natrolite ± albite. The main jadeite vein center (lower two thirds of image) is composed of scattered Cr-bearing eckermannite, abundant Cr-bearing jadeite, and sparse small bright emerald green kosmochlor, all extensively veined with natrolite ± albite ± Cr-free jadeite.
(unpolarized light)

Burma kosmochlor and eckermannite jadeitite in thin section

same as previous FKM-84 image (under crossed polars).

 




Pribyslavice Czech Republic oxy-schorl granite in thin section

sample: FKM-85
locality: Přibyslavice, Kutná Hora, Bohemia, Czech Republic.
rock type: B-bearing granite.
major mineralogy: Abundant scattered oxy-schorl (type locality) with quartz and perthitic orthoclase. Minor fluorapatite and ratty muscovite (likely secondary) are also present. For the tourmaline, values of M3+/∑M (where M = Fe+Mn) between 0.078 and 0.200 normalize to oxy-schorl. For values greater than 0.200, the normalization fails altogether (i.e. the “W” site fills to greater than 1), whereas for values less than 0.078, the tourmaline normalizes to a composition not entirely consistent with either schorl or oxy-schorl. The normalization presented here uses M3+/∑M = 0.200 (the maximum mathematically permissible value).
(unpolarized light)

mineral representative mineral compositions in FKM-85
fluorapatite (Ca4.84Mn2+0.11Sr0.01)[P3.01Si0.01O12](F0.73[OH]0.27)
oxy-schorl (maximum Fe3+) (Na0.73Ca0.02K0.010.24)(Fe2+1.52Al0.73Fe3+0.40Mg0.23Ti0.06Mn2+0.04Zn0.02)Al6.00
[Si5.72Al0.28O18](BO3)3(OH)3(O0.75F0.26)
“perthite” (orthoclase host) (K0.85Na0.09)[Si2.92Al1.05P0.03O8]
“perthite” (albite lamellae) (Na0.95K0.01)[Si2.91Al1.06P0.03O8]
muscovite (K0.83Na0.020.15)(Al1.95FeT0.06Mg0.010.98)[Si3.11Al0.89O10]([OH]1.95F0.04O0.01)

Pribyslavice Czech Republic oxy-schorl granite in thin section

same as previous FKM-85 image (under crossed polars).

 




Langban Sweden melanotekite in thin section

sample: FKM-86
locality: Långban, Filipstad, Värmland, Sweden.
rock type: Ba-Pb-As-Na-Fe metasomatite.
major mineralogy: Abundant phlogopite, with subordinate melanotekite, barite, hedyphane, an Na-(Ca)-zeolite, and calcite. A sparse aegirine-augite (containing 0.22 wt% Sc) is also present. This sample is mineralogically very similar to FKM-193, also from Långban, which also contains melanotekite and phlogopite, as well as cymrite.
(unpolarized light)

Langban Sweden melanotekite in thin section

same as previous FKM-86 image (under crossed polars).

 




Franklin New Jersey esperite and hardystonite in thin section

sample: FKM-87
locality: Franklin mining district, Sussex Co., NJ, USA.
rock type: test.
major mineralogy: esperite, hardystonite.
(unpolarized light)

Franklin New Jersey esperite and hardystonite in thin section

same as previous FKM-87 image (under crossed polars).

 

Franklin New Jersey esperite clinohedrite and hardystonite in thin section under UV light

same as previous FKM-87 images (under shortwave ultraviolet [SWUV] light).

 




Franklin New Jersey hancockite in thin section

sample: FKM-88
locality: Franklin mining district, Sussex, Co., NJ, USA.
rock type: test.
major mineralogy: hancockite (“epidote-Pb”), andradite, clinopyroxene, barite.
(unpolarized light)

Franklin New Jersey hancockite in thin section

same as previous FKM-88 image (under crossed polars).

 




Bastnas Sweden ferri-allanite and cerite in thin section

sample: FKM-89
locality: Bastnäs, Riddarhyttan, Skinnskatteberg, Västmanland, Sweden.
rock type: test.
major mineralogy: ferriallanite-(Ce), cerite-(Ce), tremolite, calcite, and an additional unknown REE-rich mineral.
(unpolarized light)

Bastnas Sweden ferri-allanite and cerite in thin section

same as previous FKM-89 image (under crossed polars).

 




Point of Rock quarry New Mexico mangan-neptunite syenite in thin section

sample: FKM-90
locality: Point of Rock quarry, Springer, Colfax Co., NM, USA.
rock type: test.
major mineralogy: specimen acquired for mangan-neptunite.
(unpolarized light)

Point of Rock quarry New Mexico mangan-neptunite syenite in thin section

same as previous FKM-90 image (under crossed polars).

 




Vastanaberget Sweden manganese-bearing andalusite in thin section

sample: FKM-91
locality: Västanåberget, Näsum, Bromölla, Skåne, Sweden.
rock type: andalusite-muscovite schist.
major mineralogy: Scattered yellowish-green Mn-rich andalusite along with abundant muscovite. Rare clinochlore and scattered large monazite (variably Ce-dominant to La+Nd-dominant) are present.
(unpolarized light)

mineral representative mineral compositions in FKM-91
La-dominant monazite [monazite-(La)] ss (La0.28Nd0.25Ce0.23Pr0.08Ca0.06Th0.05Sm0.04Y0.03Gd0.02[HREE]0.01)[P0.91As5+0.04Si0.01O4]
Ce-dominant monazite [monazite-(Ce)] ss (Ce0.30La0.25Nd0.20Pr0.06Ca0.06Th0.05Sm0.03Y0.03Gd0.02[HREE]0.01)[P0.91As5+0.06Si0.01O4]
andalusite (Al1.81Mn3+0.15Fe3+0.03)O[Si0.98Al0.02O4]
muscovite (K0.67Na0.030.30)(Al1.90FeT0.10Mg0.08Ti0.02MnT0.010.88)[Si3.15Al0.85O10]([OH]1.95O0.05F0.01)
clinochlore (Mg4.45Al1.37MnT0.05FeT0.05Zn0.010.07)[Si2.72Al1.28O10]([OH]7.93F0.06Cl0.01O0.01)

Vastanaberget Sweden manganese-bearing andalusite in thin section

same as previous FKM-91 image (under crossed polars).

 




Tetetice near Klatovy Czech Republic goldmanite and mukhinite in thin section

sample: FKM-92
locality: Tetětice (Struhadlo?), near Klatovy, Bohemia, Czech Republic.
rock type: “skarn”? Greenschist to amphibolite facies U-V-metasomatized calcareous meta-arenite?
major mineralogy: Predominately quartz, calcite, tremolite and pyrrhotite, with minor sphalerite, uraninite, and apatite. Of notable interest is scattered goldmanite, and very sparse Cr-REE-bearing mukhinite. Mukhinite is also present in sample FKM-1, and may be more widespread in V-rich metamorphic and metasomatic rocks than typically reported.
(unpolarized light)

Tetetice near Klatovy Czech Republic goldmanite and mukhinite in thin section

same as previous FKM-92 image (under crossed polars).

 




Pallavaram India charnockite in thin section

sample: FKM-93
locality: Pallavaram, Chennai, Tamil Nadu, India.
rock type: test.
major mineralogy: specimen acquired for ferro-ferri-tschermakite, but no amphibole is present in this sample.
(unpolarized light)

Pallavaram India charnockite in thin section

same as previous FKM-93 image (under crossed polars).

 




Broken Hill spessartine in thin section

sample: FKM-94
locality: Broken Hill, Yancowinna Co., NSW, Australia.
rock type: test.
major mineralogy: specimen acquired for spessartine.
(unpolarized light)

Broken Hill spessartine in thin section

same as previous FKM-94 image (under crossed polars).

 




Isua greenstone Greenland banded iron formation BIF in thin section

sample: FKM-95 (billet from Univ. Arizona petrology collection, courtesy of S. Baldwin, Syracuse Univ.)
locality: Isua greenstone belt, Greenland.
rock type: magnetite-amphibole-quartz gneiss. Greenschist to amphibolite facies meta-BIF (banded iron formation). At ~3.7Ga, the Isua greenstone belt is one of the oldest preserved rock sequences in the world, and is a geologically important example of Archean tectonics.
major mineralogy: Bands of quartz alternating with bands of intergrown magnetite and actinolite, with patches of calcite and scattered hydroxylapatite. A thin quartz vein roughly perpendicular to the dominant planar fabric slightly offsets the bands.
(unpolarized light)

mineral representative mineral compositions in FKM-95
magnetite Fe2+1.00(Fe3+1.99Al0.01)O4
hydroxylapatite (Ca4.97Mn2+0.01)[P3.00O12]([OH]0.54F0.38Cl0.08)
actinolite (Na0.05K0.010.94)(Ca1.84Fe2+0.10Mn2+0.06)(Mg2.54Fe2+2.40Al0.06)[Si7.87Al0.12O22]([OH]1.99Cl0.01)

Isua greenstone Greenland banded iron formation BIF in thin section

same as previous FKM-95 image (under crossed polars).

 




Ontario Canada granulite facies meta-gabbro with corona texture in thin section

sample: FKM-96 (billet from Univ. Arizona petrology collection, courtesy of L. Anovitz; sample ALG-85A2)
locality: Frank MacDougall Parkway roadside, Algonquin Provincial Park, Ontario, Canada.
rock type: granulite facies meta olivine ferro-gabbro.
major mineralogy: Originally olivine, cpx, (calcic?) plagioclase, ilmenite, and minor V+Cr-bearing magnetite (and possibly a bit of late-stage k-spar… it’s unclear if the minor k-spar that’s present is remnant original igneous or if it is later metasomatic accompanying the metamorphism). Due to subsequent granulite facies metamorphism (+ metasomatism?), multiple mineral corona developed between the olivine and the plagioclase, and the ilmenite and the plagioclase. Between the olivine and plagioclase, reaction rims of orthopyroxene, pargasite ± Ti-rich biotite, and garnet grew outwards from the olivine. Between the ilmenite and olivine, reaction rims of Ti-rich biotite ± pargasite grew outwards from the ilmenite. The cpx developed clouding from minute exsolution (but developed no corona), and micro-crystals of hercynite grew throughout the plagioclase. Minor apatite and Cu- and Fe-rich sulfides (several with Ni), presumably part of the primary igneous rock, seem largely unaffected by the metamorphism (although depending on the peak T, minor pyrite present may have crystallized during the cooling of the igneous rock [and was subsequently preserved during metamorphism… this would be a peak T < ~740 °C scenario], or it may have formed as a retrograde metamorphic mineral from the sulfidation of earlier igneous Fe-(Ni) sulfides… this would be a peak T > ~740 °C scenario). Likely the result of the high metamorphic grade, note that among most of the minerals, zoning is overall very muted (although the cpx fortuitously straddles a nomenclature boundary so gives the appearance of being more compositionally variable than it really is). Sparse retrograde chlorite is also present. One tiny rutile (too small to analyze well without unavoidable plagioclase overlap; however, also with >588 ppm Mn and >345 ppm Nb) was observed. The extensive accompanying analytical data were collected, normalized and interpreted entirely by a group of five undergraduate geology students as part of an analytical petrology class project (Spring 2011)… nice job, class!
(unpolarized light)

mineral representative mineral compositions in FKM-96
pentlandite (in pyrite) (Ni4.78Fe3.99Co0.22)S8.00
chalcopyrite Cu0.98Fe1.00S2.00
pyrrhotite (Fe0.86Ni0.01)S1.00
pyrite (with pentlandite inclusion) (Fe0.92Ni0.07Co0.01)S2.00
pyrite (inclusion-free) (Fe0.98Ni0.03)S2.00
hercynite (inclusions in plagioclase) (Fe2+0.72Mg0.27)(Al1.88Fe3+0.12)O4
magnetite Fe2+1.00(Fe3+1.85V0.05Al0.04Cr0.02Ti0.02Fe2+0.02)O4
ilmenite (Fe2+0.98Mn2+0.01Fe3+0.01)(Ti0.99Fe3+0.01)O3
fluorapatite (Ca4.92Na0.05Y0.01La0.01Ce0.01Nd0.01)[P2.98Si0.02O12](F0.82[OH]0.15Cl0.03)
fayalite (Mg0.83Fe2+0.15Mn2+0.01)Fe2+1.00[Si1.00O4]
almandine (Fe2+1.70Mg0.69Ca0.53Mn2+0.08)(Al1.99Fe3+0.01)[Si2.99Al0.01O12]
“hypersthene” (Mg0.97Ca0.02Mn2+0.01)(Fe2+0.83Mg0.11Al0.05)[Si1.97Al0.03O6]
diopside-rich cpx ss (Ca0.85Mg0.08Na0.07Mn2+0.01)(Mg0.59Fe2+0.31Al0.07Fe3+0.02Ti0.01)[Si1.96Al0.04O6]
augite-rich cpx ss (Ca0.81Mg0.11Na0.08Mn2+0.01)(Mg0.56Fe2+0.32Al0.07Fe3+0.04Ti0.01)[Si1.95Al0.05O6]
magnesio-hastingsite
(adjacent to magnetite)
(Na0.58K0.250.17)(Ca1.75Na0.25)(Mg2.06Fe2+1.23Fe3+0.80Al0.51Ti0.36V0.01Mn2+0.01)
[Si6.08Al1.91O22]([OH]1.23O0.71F0.05Cl0.01)
magnesio-hastingsite
(adjacent to opx)
(Na0.50K0.320.18)(Ca1.78Na0.22)(Mg2.22Fe2+1.10Fe3+0.80Al0.47Ti0.38V0.01Mn2+0.01)
[Si6.09Al1.90O22]([OH]1.20O0.75F0.03Cl0.01)
magnesio-hastingsite
(adjacent to garnet)
(Na0.48K0.320.20)(Ca1.79Na0.21)(Mg2.22Fe2+1.12Fe3+0.77Al0.48Ti0.38V0.02Mn2+0.01)
[Si6.13Al1.87O22]([OH]1.20O0.75F0.04Cl0.01)
phlogopite (K0.93Ba0.03Na0.020.02)(Mg1.18FeT1.23Ti0.45Al0.040.10)[Si2.77Al1.23O10]([OH]1.07O0.90F0.03Cl0.01)
clinochlore (Ca0.02K0.01Na0.01)(Mg2.71FeT1.98Al0.69MnT0.020.60)[Si3.45Al0.55O10]([OH]7.99F0.01)
orthoclase (K0.95Na0.03)[Si2.97Al1.02O8]
“oligoclase” (most Ca-rich) (Na0.72Ca0.28K0.03)[Si2.70Al1.30O8]
“oligoclase” (most Na-rich) (Na0.77Ca0.20K0.04)[Si2.79Al1.21O8]

Ontario Canada granulite facies meta-gabbro with corona texture in thin section

same as previous FKM-96 image (under crossed polars).

 




Bohemia Czech Republic garnetite eclogite in thin section

sample: FKM-97 (billet from Univ. Arizona petrology collection, Krentz collection, sample K-249)
locality: Bohemia, Czech Republic.
rock type: hedenbergite-garnet “eclogite”. This rock is purported to be an eclogite (and indeed it may be), but it is compositionally very different from a typical metabasite-protolith eclogite (for example, see sample FKM-34). In some respects the rock resembles a skarn-like calc-silicate, but even if this rock was originally of metasomatic origin, it still appears to have undergone subsequent high grade metamorphism (to mute any pre-existing zoning). One could imagine this rock is perhaps an eclogite facies metasomatic garnetite.
major mineralogy: This rock is very dense, notably deeply-colored, and nearly all garnet (straddling the grossular-andradite composition boundary, with a significant almandine component), with less abundant slightly-Na-enriched hedenbergite (but not Na-rich enough to be considered the omphacite/aegirine-augite of classic mafic eclogite). Scattered apatite and epidote are also present. The cpx is unzoned; the garnet is at best weakly patchy zoned, although small garnet crystals completely enclosed in cpx do differ somewhat in composition from the more abundant, larger, external (to cpx) garnet masses.
(unpolarized light)

mineral representative mineral compositions in FKM-97
fluorapatite (Ca4.98Sr0.01)[P2.99Si0.01O12](F0.65[OH]0.34)
grossular
(isolated inclusions in cpx)
(Ca2.95Fe2+0.03Mn2+0.02)(Al1.39Fe3+0.51Ti0.08Mg0.01Fe2+0.01)[Si2.92Al0.060.01O11.94F0.06]
grossular-rich garnet ss
(bulk)
(Ca2.59Fe2+0.38Mn2+0.02Mg0.01)(Al1.05Fe3+0.91Ti0.02Mg0.01)[Si2.99Al0.01O11.99F0.01]
andradite-rich garnet ss
(patchy in bulk grossular)
(Ca2.67Fe2+0.30Mn2+0.02Mg0.01)(Fe3+1.21Al0.76Ti0.02)[Si2.97Al0.02O11.99F0.01]
epidote Ca1.00(Ca0.96Sr0.02)Al1.02Al1.00(Fe3+0.74Al0.25Ti0.01)O[Si0.99Al0.01O4][Si1.98Al0.02O7](OH)
hedenbergite (Ca0.93Na0.07)(Fe2+0.46Mg0.43Fe3+0.11Al0.01)[Si1.95Al0.05O6]

Bohemia Czech Republic garnetite eclogite in thin section

same as previous FKM-97 image (under crossed polars).

 




Kola Russia eudialyte lujavrite pegmatite in thin section

sample: FKM-98
locality: Kola Peninsula, Murmanskaja Oblast’, Russia.
rock type: intrusive eudialyte-pyroxene pegmatite (lujavrite?)
major mineralogy: test.
(unpolarized light)

Kola Russia eudialyte lujavrite pegmatite in thin section

same as previous FKM-98 image (under crossed polars).

 




Mayavetch River New Caledonia garnet glaucophane blueschist in thin section

sample: FKM-99 (billet from Univ. Arizona petrology collection, courtesy of S. Baldwin; sample NC-55)
locality: Mayavetch River, Pouébo terrane, northern New Caledonia.
rock type: garnet-glaucophane schist. Blueschist facies retrogressed eclogite facies metabasite. Compare this sample to the more phengite-rich FKM-100, also from the Mayavetch River area.
major mineralogy: test.
(unpolarized light)

Mayavetch River New Caledonia garnet glaucophane blueschist in thin section

same as previous FKM-99 image (under crossed polars).

 




Mayavetch River New Caledonia garnet glaucophane blueschist in thin section

sample: FKM-100 (billet from Univ. Arizona petrology collection, courtesy of S. Baldwin; sample NC-57)
locality: Mayavetch River, Pouébo terrane, northern New Caledonia. Compare this sample to the less phengite-rich FKM-99, also from the Mayavetch River area.
rock type: garnet-phengite-glaucophane schist. Blueschist facies.
major mineralogy: test.
(unpolarized light)

Mayavetch River New Caledonia garnet glaucophane blueschist in thin section

same as previous FKM-100 image (under crossed polars).

 


next page (samples FKM-101 to FKM-200)