samples FKM-76 to FKM-100

 

Check out the thin section scans introduction page for more information on the variety of samples featured here, how the scans were taken & processed for web display, and what additional optical and analytical data I hope to include in the figure captions as I continue to update the site and add to the collection of thin sections.

There’s also a fully searchable index covering the complete thin section set, listing for each sample its locality, the anticipated major minerals, a brief generalized geologic environment description, and where appropriate, the nature of any unusual element enrichments.

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Broken Hill inesite in thin sectionBroken Hill inesite in thin section

left image: unpolarized light; right image: under crossed polarizers; use slider in center to view more of either image

sample: FKM-76
locality: Broken Hill, Yancowinna Co., NSW, Australia.
rock type: test.
major mineralogy: inesite.
accompanying videos: Short videos featuring the mineral associations and optical properties of the inesite in this thin section offer a more detailed look at this sample.

 



Ilimaussaq Greenland eudialyte kakortokite in thin sectionIlimaussaq Greenland eudialyte kakortokite in thin section

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sample: FKM-77
locality: Kangerdluarsuk Fjord, Ilímaussaq complex, Narsaq, Kujalleq, Greenland.
rock type: kakortokite. Cumulate eudialyte-nepheline syenite.
major mineralogy: Eudialyte, aegirine (but originally thought to be arfvedsonite), nepheline, plagioclase.
accompanying videos: Short videos featuring the mineral associations and optical properties of the eudialyte in this thin section offer a more detailed look at this sample.
accompanying videos: Short videos featuring the mineral associations and optical properties of the aegirine and nepheline in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-77
hydroxylbastnäsite-(Ce) (Ce0.43La0.33Nd0.07Ca0.05Na0.04Pr0.03Sr0.03)[CO3]([OH]0.51F0.49)
eudialyte
(main moderate z interior;
estimated z̄ ≈ 14.96)
(Na11.33[H3O]+~0.51K0.16)(Na2.34Ce0.20Y0.15La0.10Nd0.07[HREE]~0.05Sr0.03Pr0.02Gd0.02Sm0.01)
(Ca5.49Na0.51)(Fe2+~2.24Na0.29Mn2+0.29Fe3+~0.16Mg0.02)(Zr2.79Nb0.14Hf~0.03Ti0.03Ta~0.01)
(Si0.77Al0.16Nb0.08)[(Si1.00O)(Si9.00O27)2][Si3.00O9]2([OH]~2.24Cl0.46[H2O]~0.29O~0.01)Cl1.00
eudialyte
(patchy mod-low z interior;
estimated z̄ ≈ 14.66)
(Na11.08[H3O]+~0.74K0.090.09?)(Na2.38Ce0.18Y0.15La0.08Nd0.07[HREE]~0.05Sr0.03Pr0.02Gd0.02Sm0.01)
(Ca5.49Na0.51)(Fe2+~2.18Na0.38Mn2+0.26Fe3+~0.16Mg0.02)(Zr2.82Nb0.11Hf~0.03Ti0.03Ta~0.01)
(Si0.82Al0.14Nb0.03)[(Si1.00O)(Si9.00O27)2][Si3.00O9]2([OH]~1.91[H2O]~0.61Cl0.48)Cl1.00
eudialyte
(inner mod-high z rim;
estimated z̄ ≈ 15.16)
(Na11.33K0.09[H3O]+~0.080.50?)(Na2.28Ce0.23Y0.15La0.11Nd0.08[HREE]~0.05Sr0.04Pr0.03Gd0.02Sm0.01)
(Ca5.52Na0.48)(Fe2+~1.89Na0.61Mn2+0.36Fe3+~0.14)(Zr2.80Nb0.15Hf~0.03Ti0.01Ta~0.01)
(Si0.76Al0.15Nb0.09)[(Si1.00O)(Si9.00O27)2][Si3.00O9]2([OH]~1.63[H2O]~0.90Cl0.45O~0.01)(Cl0.98F0.02)
eudialyte
(outer moderate z rim;
estimated z̄ ≈ 14.85)
(Na10.62K0.121.26?)(Na2.34Ce0.20Y0.14La0.10Nd0.08[HREE]~0.05Sr0.03Pr0.02Gd0.02Sm0.01)
(Ca5.49Na0.51)(Fe2+~1.87Na0.64Mn2+0.35Fe3+~0.14)(Zr2.83Nb0.11Hf~0.03Ti0.02Ta~0.01)
(Si0.82Al0.11Nb0.07)[(Si1.00O)(Si9.00O27)2][Si3.00O9]2([H2O]~1.90[OH]~0.93Cl0.17)(Cl0.97F0.03)
catapleiite analysis pending
aegirine (most Na-rich) (Na0.99Ca0.01)(Fe3+0.92Al0.05Fe2+0.01Ti0.01)[Si2.00O6]
aegirine (most Ca-rich) (Na0.90Ca0.09)(Fe3+0.80Fe2+0.12Al0.05Ti0.02)[Si2.00O6]
pectolite Na1.00(Ca0.80Mn2+0.20)(Ca0.92Fe2+0.07Zr0.01)[Si3.00O8](OH)
orthoclase (K0.97Na0.01)[Si2.98Al1.02O8]
albite (Na1.01K0.01)[Si2.97Al1.01Fe3+0.01O8]
nepheline (Na0.76K0.210.03)[Si1.01Al0.98Fe3+0.01O4]
analcime? (rim [alteration?]
between albite & nepheline)
(Na0.790.21)[Si1.95Al1.05O6] . ~1H2O
gmelinite-K(?)
(possibly chabazite-K)
([K2]0.36Ca0.58[Na2]0.10)[Si3.87Al2.13O12] . ~5.5H2O

 



Bozeman mine Montana corundum gneiss in thin sectionBozeman mine Montana corundum gneiss in thin section

left image: unpolarized light; right image: under crossed polarizers; use slider in center to view more of either image

sample: FKM-78
locality: Bozeman Corundum Company mine, Gallatin Gateway, Gallatin Co., MT, USA.
rock type: corundum-bearing feldspathic gneiss.
major mineralogy: Porphyroblasts of corundum (increasing abundance with decreasing size) in a feldspar-dominant matrix largely composed of microperthitic orthoclase with additional plagioclase (“oligoclase”). Ti-rich biotite with Fe ≈ Mg is also abundant. Scattered large rutile, magnetite, and tiny apatite are present.
accompanying videos: Short videos featuring the mineral associations and optical properties of the corundum, biotite and orthoclase in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-78
corundum (Al1.99Fe3+0.01)O3
rutile (Ti0.98V0.01)O2
magnetite Fe2+1.00(Fe3+1.33Ti0.30Fe2+0.29V0.06Cr0.01Al0.01)O4
fluorapatite (Ca4.71Na0.07FeT0.06Mn2+0.03Ce0.01La0.01Nd0.01Y0.01)[P0.997O4]3(F0.52Cl0.26[OH]0.22)
biotite (K0.95Na0.020.03)(FeT1.22Mg1.00Al0.35Ti0.29V0.02Cr0.01Ni0.01MnT0.010.09)
[Si2.65Al1.35O10]([OH]1.37O0.57Cl0.04F0.02)
“perthite” (orthoclase host) (K0.81Na0.18Ba0.01)[Si2.95Al1.05O8]
“perthite” (albite lamellae) (Na0.99Ca0.01K0.01)[Si2.95Al1.05P0.01O8]
“oligoclase” (main) (Na0.78Ca0.22K0.01)[Si2.73Al1.26P0.01O8]

 



Leucite Hills Wyoming leucitite in thin sectionLeucite Hills Wyoming leucitite in thin section

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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.

 



Eifel Germany hauyne phonolite in thin sectionEifel Germany hauyne phonolite in thin section

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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 (notable as glassy bright blue equant grains in the hand sample, but sparse in this particular thin section and essentially indistinguishable from the feldspar and voids in these images), and minor apatite, sub-silicic diopside (largely homogeneous but with small scattered more Fe-rich zones), and magnetite. No nepheline or other feldspathoids besides haüyne are apparent in the sample.
accompanying videos: Short videos featuring the mineral associations and optical properties of the sanidine in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-80
magnetite (Fe2+0.86Mg0.08Mn2+0.06)(Fe3+1.36Fe2+0.26Ti0.26Al0.11V0.01)O4
fluorapatite (Ca4.89Na0.05Ce0.01La0.01MnT0.01FeT0.01)[P0.967Si0.02S0.013O4]3(F0.56[OH]0.40Cl0.04)
diopside (main;
most Mg-rich)
(Ca0.90Na0.07Mn2+0.03)(Mg0.47Fe2+0.23Fe3+0.19Ti0.06Al0.04)[Si1.71Al0.29O6]
diopside
(most Fe-rich)
(Ca0.90Na0.09Mn2+0.01)(Mg0.39Fe2+0.30Fe3+0.22Ti0.06Mn2+0.03)[Si1.73Al0.26O6]
sanidine (K0.62Na0.33Ca0.04Ba0.01Sr0.01)[Si2.91Al1.08Fe3+0.01O8]
haüyne* (Na5.51K0.470.02)[Si5.98Al5.97Fe3+0.05O24] . (Ca1.61Na0.19Sr0.01Mg0.01)([SO4]2-1.52?[S3?]2-?0.15?Cl0.11F0.01)

 



Wippertal Germany carpholite in thin sectionWippertal Germany carpholite in thin section

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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).
accompanying videos: Short videos featuring the mineral associations and optical properties of the carpholite in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-81
“Fe-oxide/oxyhydroxide” not analyzed
fluorapatite (Ca4.87Mn2+0.07[M+HREE]0.01)[P1.007Si0.003O4]3(F0.96[OH]0.04)
carpholite-dominant ss (main) (Mn2+0.56Mg0.29Fe2+0.13Fe3+0.01Ti0.01)(Al1.99Fe3+0.01)[Si1.97Al0.03O6]([OH]3.95F0.05)
magnesiocarpholite-dominant 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)
quartz not analyzed

 



Madagascar dumortierite in thin sectionMadagascar dumortierite in thin section

left image: unpolarized light; right image: under crossed polarizers; use slider in center to view more of either image

sample: FKM-82
locality: Presumably from the Itremo massif but labeled more specifically as “Itremo commune” (although the Itremo massif actually spans three communes); however, this rock appears to be more mineralogically consistent with the dumortierite+sillimanite in pegmatite described from adjacent Riampotsy, Itremo massif, Mangatabohangy commune, Ambatofinandrahana district, Fianarantsoa province, Madagascar.
rock type: test.
major mineralogy: specimen acquired for dumortierite and sillimanite.
accompanying videos: Short videos featuring the mineral associations and optical properties of the dumortierite in this thin section offer a more detailed look at this sample.

 



Langban Sweden magnesioferrite in thin sectionLangban Sweden magnesioferrite in thin section

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

mineral representative mineral compositions in FKM-83
litharge? Pb0.99O
hematite (Fe3+1.98Ti0.01Mg0.01)O3
magnesioferrite (Mg0.82Mn2+0.14Fe2+0.02Zn0.02)(Fe3+1.97Al0.03)O4
calcite (main) (Ca0.96Mg0.02Pb0.01)[CO3]
calcite (irregular rims) (Ca0.98Mg0.02)[CO3]
dolomite (Ca0.99Pb0.01)(Mg0.98Ca0.01)[CO3]2
hedyphane (lower z; poor
stoichiometry… re-analysis
may be desirable)
Pb3.00(Ca1.53Pb0.66Ce0.07)[As5+0.71?P0.177As3+0.063?Si0.033V5+0.017O4]3Cl1.10
hedyphane (higher z; poor
stoichiometry… re-analysis
may be desirable)
Pb3.00(Ca1.38Pb0.91Ce0.07)[As5+0.77?P0.097As3+0.07?Si0.033V5+0.017O4]3Cl1.11
forsterite (Mg0.99Mn2+0.01)Mg1.00[Si1.00O4]
phlogopite (main low z core) (K0.93Ba0.02Na0.02Pb0.010.02)(Mg2.95FeT0.05)[Si2.97Al0.91Fe3+0.12O10]([OH]1.94F0.05)
phlogopite (mod z
erratic inner band)
(K0.87Ba0.10Na0.02Pb0.01)(Mg2.88FeT0.11)[Si2.89Al1.10Fe3+0.01O10]([OH]1.93F0.06)
phlogopite (mod-high z
erratic inner patches)
(K0.69Ba0.28Na0.02Pb0.02)(Mg2.85FeT0.12Al0.010.02)[Si2.69Al1.31O10]([OH]1.90F0.10)
phlogopite (mod z inner rim) (K0.73Ba0.24Na0.02Pb0.02Ca0.01)(Mg2.87FeT0.110.02)[Si2.72Al1.28O10]([OH]1.92F0.08)
phlogopite (high z outer rim;
at kinoshitalite nomenclature
boundary)
(K0.49Ba0.48Na0.02Ca0.02Pb0.01)(Mg2.83FeT0.08Al0.060.02)[Si2.44Al1.56O10]([OH]1.89F0.11)

 



Burma kosmochlor and eckermannite jadeitite in thin sectionBurma kosmochlor and eckermannite jadeitite in thin section

left image: unpolarized light; right image: under crossed polarizers; use slider in center to view more of either image

sample: FKM-84
locality: Tawmaw area, 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 the sample) consists of medium-green “blobs” of Cr-bearing eckermannite surrounded by a mixture of paler green low-Cr eckermannite gradational to low-Cr glaucophane, along with some low-Cr jadeite and small masses of bright green kosmochlor. Minor Na-rich zeolites, dominated by natrolite and some edingtonite, are interspersed in this zone. The main jadeite vein center (lower two thirds of sample) is of similar mineralogy but with more jadeite, somewhat larger masses of kosmochlor, patches of Cr-rich glaucophane also gradational to eckermannite, and additional veinlets of zeolites. The amphiboles did not normalized well to any simple cation-based normalization schemes, so they were instead normalized to 23 [O] equivalents (assigning [Fe+Mn]3+/∑[Fe+Mn] = 0.0); this initially resulted in the VIM site being somewhat under-filled (~0.10 to ~0.30 apfu). Although it’s not known whether the VIM site is actually slightly vacant, the approach used here was to convert sufficient XIINa to VINa to fill the VIM site. One outcome of this assumption is that a few Na-rich amphiboles initially just over the eckermannite-glaucophane composition boundary re-calculated to glaucophane.
accompanying videos: Short videos featuring the mineral associations and optical properties of the kosmochlor and eckermannite in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-84
glaucophane-dominant
B(NaNa)-amph ss (most Cr-rich)
(Na0.11K0.010.88)(Na1.91Ca0.09)(Na0.12Mg2.63Al1.56Cr0.42Fe2+0.25Ti0.01Ni0.01)
[Si7.88Al0.12O22]([OH]1.97O0.03)
glaucophane-dominant
B(NaNa)-amph ss (most Al-rich;
near eckermannite boundary)
(Na0.450.55)(Na1.88Ca0.12)(Na0.21Mg2.64Al1.64Fe2+0.50Cr0.01)
[Si7.93Al0.07O22]([OH]1.99O0.01)
eckermannite-dominant
B(NaNa)-amph ss (most Cr-rich;
near glaucophane boundary)
(Na0.51K0.020.47)(Na1.71Ca0.29)(Na0.10Mg2.71Al1.06Cr0.60Fe2+0.51Ti0.02)
[Si7.59Al0.40O22]([OH]1.96O0.04)
eckermannite-dominant
B(NaNa)-amph ss (most Al-rich)
(Na0.650.35)(Na1.87Ca0.13)(Na0.29Mg2.75Al1.54Fe2+0.36Cr0.05Ti0.01Ni0.01)
[Si7.89Al0.11O22]([OH]1.96F0.03O0.01)
jadeite (most Al-rich) (Na0.96Fe2+0.02)(Al0.82Cr0.19Ti0.01)[Si1.99Al0.02O6]
jadeite (most Cr-rich) (Na0.93Ca0.06Mg0.02)(Al0.55Cr0.30Fe3+0.08Mg0.05Fe2+0.01Ti0.01)[Si1.98Al0.02O6]
kosmochlor (most Al-rich) (Na0.92Ca0.06Mg0.03)(Cr0.58Al0.26Fe3+0.07Mg0.06Fe2+0.02Ti0.02)[Si1.96Al0.04O6]
kosmochlor (most Cr-rich) (Na0.96Ca0.02)(Cr0.77Al0.15Fe2+0.05Mg0.02)[Si2.02O6]
natrolite
edingtonite

 



Pribyslavice Czech Republic oxy-schorl granite in thin sectionPribyslavice Czech Republic oxy-schorl granite in thin section

left image: unpolarized light; right image: under crossed polarizers; use slider in center to view more of either image

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).
accompanying videos: Short videos featuring the mineral associations and optical properties of the oxy-schorl in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-85
fluorapatite (Ca4.84Mn2+0.11Sr0.01)[P1.003Si0.003O4]3(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)
muscovite (K0.83Na0.020.15)(Al1.95FeT0.06Mg0.010.98)[Si3.11Al0.89O10]([OH]1.95F0.04O0.01)
“perthite” (orthoclase host) (K0.85Na0.09)[Si2.92Al1.05P0.03O8]
“perthite” (albite lamellae) (Na0.95K0.01)[Si2.91Al1.06P0.03O8]
quartz not analyzed

 



Langban Sweden melanotekite in thin sectionLangban Sweden melanotekite in thin section

left image: unpolarized light; right image: under crossed polarizers; use slider in center to view more of either image

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.
accompanying videos: Short videos featuring the mineral associations and optical properties of the melanotekite in this thin section offer a more detailed look at this sample.

 



Franklin New Jersey esperite and hardystonite in thin sectionFranklin New Jersey esperite and hardystonite in thin section

left image: unpolarized light; right image: under crossed polarizers; use slider in center to view more of either image

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

under shortwave ultraviolet [SWUV] illumination

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

 



Franklin New Jersey hancockite in thin sectionFranklin New Jersey hancockite in thin section

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sample: FKM-88
locality: Franklin mining district, Sussex, Co., NJ, USA.
rock type: test.
major mineralogy: hancockite (for a while “epidote-(Pb)”), epidote-(Sr) (as near-rim bands within zoned crystals of Pb+Sr-bearing epidote grading outwards to Sr-bearing hancockite), andradite, barite, franklinite, hendricksite.
accompanying videos: Short videos featuring the mineral associations and optical properties of the hancockite in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-88
franklinite (Zn0.73Mn2+0.27)(Fe3+1.75Al0.14Mn3+0.04Ti0.03Mn2+0.03)O4
barite (Ba0.96Sr0.04)[S1.00O4]
andradite-dominant
garnet ss (main interior)
(Ca2.35Mn2+0.64Zn0.01)(Fe3+1.61Al0.35Mn3+0.02Ti0.01)[Si0.993Al0.003O4]3
grossular-dominant
garnet ss (rim)
(Ca2.36Mn2+0.62Na0.01)(Al1.01Fe3+0.97Ti0.02)[Si0.987Al0.01O4]3
hancockite-dominant
epidote group ss
(rim; most Pb-rich)
Ca1.00(Pb0.82Sr0.16Ba0.02)(Al0.72Fe3+0.28)Al1.00(Fe3+0.81Mn3+0.17Mg0.01Zn0.01Ti0.01)O1.00
[Si1.97Al0.03O7][Si1.00O4](OH)
epidote-(Sr)-dominant
epidote group ss
(near rim)
(Ca0.89Mn2+0.10)(Sr0.38Ca0.33Pb0.27)Al1.01Al1.00(Fe3+0.93Mn3+0.05Al0.03)O1.00[Si1.98Al0.02O7][Si1.00O4](OH)
epidote-dominant
epidote group ss (core)
(Ca0.98Mn2+0.02)(Ca0.89Sr0.08Pb0.03)Al1.00Al1.00(Fe3+0.92Al0.05Mn3+0.03)O1.00[Si2.00O7][Si1.00O4](OH)
“clinopyroxene” (pending verification and analysis)
hendricksite (K0.92Ba0.010.07)(Zn1.34MnT0.80FeT0.31Mg0.31Al0.12Ti0.030.09)[Si2.82Al1.18O10]([OH]1.93O0.07)

 



Bastnas Sweden ferri-allanite and cerite in thin sectionBastnas Sweden ferri-allanite and cerite in thin section

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sample: FKM-89
locality: Bastnäs, Riddarhyttan, Skinnskatteberg, Västmanland, Sweden.
rock type: best described as a REE metasomatite.
major mineralogy: The specimen is dominated by ferriallanite-(Ce) compositionally gradational to ferriallanite-(La); one analysis yields 10.708 wt% La and 10.706 wt% Ce (see below), which normalizes to the La-dominant (although barely) end-member. From only the two analyses shown, it also appears that the more La-rich ferriallanite is somewhat more enriched in Mg as well. Additional analyses may likely yield material more unequivocally La-dominant, and may also shed more light on the relationship between the relative REE abundances and the mineral’s Mg/Fe ratio. One possibility for this relationship is the effect of spatial or temporal variation in local redox state, even on the scale of a thin section; for example, more oxidizing conditions might favor La-dominated compositions (due to Ce progressively sequestered as Ce4+ in cerianite, which is reported at Bastnäs), accompanied simultaneously by more Mg-dominated compositions (due to less Fe2+ available to charge balance the REE in allanite, and so moving towards a dissakisite composition in this already Mg-rich environment). Although cerianite as a sink for Ce4+ was not observed in this particular sample, a number of relatively La-dominant REE phases occur at Bastnäs, indicating that at least locally, Ce was not always readily available. This local enrichment of La is also reflected by the presence of bastnäsite-(La) in this sample, although here again with La only just slightly more abundant then Ce (and note also that F is essentially sub-equal to OH, suggesting that with further analyses, both hydroxylbastnäsite-(Ce) and hydroxylbastnäsite-(La) [a new mineral] could be discovered as additional species at this locality). Nonetheless, abundant cerite-(Ce) and what is likely a new member of the gatelite group are additional Ce-dominant REE-bearing minerals observed in the thin section. According to current gatelite supergroup nomenclature recommendations (Bonazzi et al., 2018), this new mineral would be named “ferrigatelite-(Ce)”, reflecting a sufficiently abundant amount of Fe3+ to dominant the M1 site. Abundant Mg-rich actinolite and minor talc make up the non-REE bearing silicate material, and some calcite is also present.
accompanying videos: Short videos featuring the mineral associations and optical properties of the ferri-allanite in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-89
calcite analysis pending
bastnäsite-(La) (La0.47Ce0.46Nd0.04Pr0.03)[CO3](F0.51[OH]0.49)
cerite-(Ce) (Ce3.90La2.28Nd1.21Ca0.58Pr0.41Y0.24Sm0.22Gd0.16)
(Mg0.78Fe2+0.20Ca0.02)[Si1.00O4]3[Si1.00O3(OH)]4([OH]2.10F0.88Cl0.02)
ferriallanite-(Ce)-dominant
allanite group ss
(Ca0.95Y0.02Mn2+0.01)(Ce0.52La0.32Nd0.10Pr0.05Sm0.01Gd0.01[HREE]0.01)(Fe3+0.91Mg0.07Ti0.01)
(Al0.95Fe3+0.05)(Fe2+0.83Mg0.16)(O0.98F0.02)[Si2.00O7][Si1.00O4](OH)
ferriallanite-(La)-dominant
allanite group ss
(Ca0.87Fe2+0.03Y0.02Mn2+0.02)(La0.483Ce0.479Nd0.04Pr0.03)(Fe3+0.82Mg0.17)(Al0.81Fe3+0.19)
(Fe2+0.73Mg0.27)(O0.93F0.07)[Si2.02O7][Si1.00O4](OH)
“ferrigatelite-(Ce)”
(analysis #49)
(Ca0.92Mn2+0.020.06)(Ce1.46La1.23Nd0.14Pr0.11Sm0.01[M+HREE]0.01Y0.010.03)Fe3+1.00
(Al1.76Fe3+0.24)(Mg0.67Fe2+0.22Fe3+0.06Ti0.020.03)(O0.83F0.17)[Si2.00O7][Si1.00O4]3(OH)2
“ferrigatelite-(Ce)”
(analysis #50)
(Ca0.960.04)(Ce1.47La1.11Nd0.17Pr0.11Sm0.01Gd0.01[HREE]0.01Y0.010.10)Fe3+1.00
(Al1.78Fe3+0.22)(Mg0.63Fe3+0.30Ti0.010.06)(O0.87F0.13)[Si2.00O7][Si1.00O4]3(OH)2
actinolite 1.00(Ca1.87Fe2+0.05Mn2+0.03)(Mg4.38Fe2+0.51Fe3+0.10Al0.01Co0.01)[Si8.00O22]([OH]1.62F0.38)
talc (Mg2.73FeT0.20Co0.010.06)[Si4.02O10]([OH]1.59F0.41)

 



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

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

 



Vastanaberget Sweden manganese-bearing andalusite in thin sectionVastanaberget Sweden manganese-bearing andalusite in thin section

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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.
accompanying videos: Short videos featuring the mineral associations and optical properties of the green Mn-bearing andalusite in this thin section offer a more detailed look at this sample.

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)O1.00[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)
quartz not analyzed

 



Tetetice near Klatovy Czech Republic goldmanite and mukhinite in thin sectionTetetice near Klatovy Czech Republic goldmanite and mukhinite in thin section

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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-26, and may be more widespread in V-rich metamorphic and metasomatic rocks than typically reported.
accompanying videos: Short videos featuring the mineral associations and optical properties of the goldmanite in this thin section offer a more detailed look at this sample.

 



Pallavaram India charnockite in thin sectionPallavaram India charnockite in thin section

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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.

 



Broken Hill spessartine in thin sectionBroken Hill spessartine in thin section

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sample: FKM-94
locality: Broken Hill, Yancowinna Co., NSW, Australia.
rock type: [clino-ferro-suenoite]-pyroxmangite-spessartine gneiss.
major mineralogy: At first appearance, the somewhat friable rock looks almost like a sandstone composed almost entirely of millimeter-sized orange-red garnet grains. However in thin section, the metamorphic (or metasomatic) nature of the rock becomes more apparent, as does the observation that the “orange-red mineral” is not only garnet. Fe-rich spessartine garnet does indeed make up about 50% of the rock, but most of the rest of the rock consists of larger interlocking Fe-bearing pyroxmangite crystals heavily included with oriented clino-ferro-suenoite (formerly “manganogrunerite”). Additional somewhat larger crystals of the amphibole are also scattered in the sample. Note that for the pyroxmangite formula given below, the main Fe, Mg, Ca and Mn site assignments have not been determined by X-ray methods, but are presented this way to emphasize the nature of the seven distinct metal cation sites.
accompanying videos: Short videos featuring the mineral associations and optical properties of the spessartine, pyroxmangite and clino-ferro-suenoite in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-94
galena
sphalerite
pyrrhotite
chalcopyrite
apatite
pyroxmangite (Ca0.66Mn2+0.17Mg0.17)Mn2+1.00Mn2+1.00Mn2+1.00Fe2+1.00Fe2+1.00(Fe2+0.61Mg0.34Zn0.03Ti0.01Fe3+0.01)
[Si6.97Fe3+0.02Al0.01O21]
clino-ferro-suenoite 1.00(Mn2+1.34Fe2+0.42Ca0.22Na0.01)(Fe2+3.08Mg1.88Zn0.02Al0.02)[Si8.00O22]([OH]1.94F0.05Cl0.01)
spessartine (Mn2+1.45Fe2+0.99Ca0.43Mg0.12)(Al1.94Fe3+0.05)[Si2.96Al0.04O12]

 



Isua greenstone Greenland banded iron formation BIF in thin section

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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.
accompanying videos: Short videos featuring the mineral associations and optical properties of the actinolite in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-95
magnetite Fe2+1.00(Fe3+1.99Al0.01)O4
calcite not analyzed
hydroxylapatite (Ca4.97Mn2+0.01)[P1.00O4]3([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)
quartz not analyzed

 



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

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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!
accompanying videos: Short videos featuring the mineral associations and optical properties of the enstatite and magnesio-hastingsite in this thin section offer a more detailed look at this sample.

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
rutile not normalized; >588 ppm Mn; >345 ppm Nb
fluorapatite (Ca4.92Na0.05Y0.01La0.01Ce0.01Nd0.01)[P0.993Si0.007O4]3(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)[Si0.997Al0.003O4]3
“hypersthene” (Mg0.97Ca0.02Mn2+0.01)(Fe2+0.83Mg0.11Al0.05)[Si1.97Al0.03O6]
diopside-dominant cpx ss (Ca0.85Mg0.08Na0.07Mn2+0.01)(Mg0.59Fe2+0.31Al0.07Fe3+0.02Ti0.01)[Si1.96Al0.04O6]
augite-dominant 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]

 



Bohemia Czech Republic garnetite eclogite in thin sectionBohemia Czech Republic garnetite eclogite in thin section

left image: unpolarized light; right image: under crossed polarizers; use slider in center to view more of either image

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.
accompanying videos: Short videos featuring the mineral associations and optical properties of the hedenbergite in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-97
calcite?/aragonite? not analyzed
fluorapatite (Ca4.98Sr0.01)[P0.997Si0.003O4]3(F0.65[OH]0.34)
grossular
(isolated inclusions in cpx)
(Ca2.95Fe2+0.03Mn2+0.02)(Al1.39Fe3+0.51Ti0.08Mg0.01Fe2+0.01)[Si0.973Al0.020.003O3.98F0.02]3
grossular-dominant garnet ss
(bulk)
(Ca2.59Fe2+0.38Mn2+0.02Mg0.01)(Al1.05Fe3+0.91Ti0.02Mg0.01)[Si0.997Al0.003O3.997F0.003]3
andradite-dominant garnet ss
(patchy in bulk grossular)
(Ca2.67Fe2+0.30Mn2+0.02Mg0.01)(Fe3+1.21Al0.76Ti0.02)[Si0.99Al0.007O3.997F0.003]3
epidote Ca1.00(Ca0.96Sr0.02)Al1.02Al1.00(Fe3+0.74Al0.25Ti0.01)O1.00[Si0.99Al0.01O4][Si1.98Al0.02O7](OH)
hedenbergite (Ca0.93Na0.07)(Fe2+0.46Mg0.43Fe3+0.11Al0.01)[Si1.95Al0.05O6]

 



Kola Russia eudialyte lujavrite pegmatite in thin sectionKola Russia eudialyte lujavrite pegmatite in thin section

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

 



Mayavetch River New Caledonia garnet glaucophane blueschist in thin sectionMayavetch River New Caledonia garnet glaucophane blueschist in thin section

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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. Float sample of blueschist facies retrogressed eclogite facies metabasite(?) (S. Baldwin; pers. comm.). Compare this sample to the more phengite-rich FKM-100, also from the Mayavetch River area.
major mineralogy: test.

 



Mayavetch River New Caledonia garnet glaucophane blueschist in thin sectionMayavetch River New Caledonia garnet glaucophane blueschist in thin section

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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 (“type 1” blueschist; Baldwin et al., 2007 [← subscription required]; Clarke et al., 1997). Blueschist facies.
major mineralogy: test.
accompanying videos: Short videos featuring the mineral associations and optical properties of the glaucophane and muscovite in this thin section offer a more detailed look at this sample.

 



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