samples FKM-176 to FKM-200

 

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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Vysoký Kámen Czech Republic koechilinite and powellite in thin sectionVysoký Kámen Czech Republic koechilinite and powellite in thin section

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sample: FKM-176
locality: feldspar quarry, Vysoký Kámen, Krásno, Horní Slavkov, Czech Republic.
rock type: add rock type.
major mineralogy: specimen acquired for koechilinite and powellite.

 



Rana Norway høgtuvaite in thin sectionRana Norway høgtuvaite in thin section

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sample: FKM-177
locality: Høgtuva beryllium deposit, Rana, Nordland, Norway.
rock type: add rock type.
major mineralogy: specimen acquired for høgtuvaite.

 



Bjurliden Sweden gahnite in thin sectionBjurliden Sweden gahnite in thin section

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sample: FKM-178
locality: Bjurliden, Norsjö, Västerbotten, Sweden.
rock type: add rock type.
major mineralogy: specimen acquired for gahnite. For comparison, another gahnite-bearing sample featured here (in quartz rather than admixed with sulfides) is FKM-12. Additionally, several of the Franklin, NJ samples show a somewhat atypical orange to yellow gahnite (e.g. FKM-45 and FKM-48).

 



Crestmore California monticellite and hydroxylapatite in thin sectionCrestmore California monticellite and hydroxylapatite in thin section

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sample: FKM-179
locality: Crestmore quarries, Crestmore, Riverside Co., CA, USA.
rock type: high-grade monticellite marble. Contact aureole (high-T low-P; sanidinite(?) facies) metamorphosed siliceous carbonate, with additional metasomatic contribution from the causative intrusion.
major mineralogy: Sample is predominately calcite (pale blue in hand sample) with abundant mm-sized porphyroblasts of monticellite and a P-bearing hydroxylellestadite (incorrectly identified on the dealer label as hydroxylapatite; P-rich ellestadite from Crestmore was formerly known as “wilkeite” and was originally thought to be a distinct species). Small scattered garnet crystals occur both as inclusions in monticellite and as discrete grains in the calcite; some are variably and irregularly zoned, whereas others are nearly homogeneous. Cr, Sc, Zr and Y are variably-enriched in the garnet. Minor gypsum is present (likely secondary… occurs along a weathered surface), and sparse tiny chalcocite is scattered within the calcite. For comparison, an essentially identical monticellite-bearing sample featured here, also from Crestmore, is FKM-10.

mineral representative mineral compositions in FKM-179
“chalcocite group” not analyzed
calcite not analyzed
gypsum not analyzed
hydroxylellestadite (Ca4.98Na0.01)[Si0.40S0.383P0.21V0.003O4]3([OH]0.72F0.16Cl0.12)
monticellite Ca1.00(Mg0.90Fe2+0.08)[Si1.01O4]
grossular-dominant garnet ss (most Al+Zr-rich) (Ca2.98Mg0.02)(Al0.94Fe3+0.70Cr0.18Ti0.08Sc0.03Zr0.03Mg0.03)[Si0.967Al0.033O4]3
andradite-dominant garnet ss (most Cr+Sc-rich) (Ca2.90Mg0.06Y0.02)(Fe3+0.74Al0.68Cr0.46Sc0.06Ti0.05Zr0.01)[Si0.967Al0.033O4]3
andradite-dominant garnet ss (most Fe-rich) Ca3.00(Fe3+1.94Fe2+0.02Mg0.01)[Si1.007O4]3

 



Ilímaussaq Greenland narsarsukite in thin sectionIlímaussaq Greenland narsarsukite in thin section

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sample: FKM-180
locality: Kangerdluarsuk Fjord, Ilímaussaq complex, Narsaq, Kujalleq, Greenland.
rock type: add rock type.
major mineralogy: specimen acquired for narsarsukite.

 



Ilímaussaq Greenland naujakasite in thin sectionIlímaussaq Greenland naujakasite in thin section

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sample: FKM-181
locality: Kangerdluarsuk Fjord, Ilímaussaq complex, Narsaq, Kujalleq, Greenland.
rock type: add rock type.
major mineralogy: specimen acquired for naujakasite.

 



Ludvika Sweden knebelite and hematite in thin sectionLudvika Sweden knebelite and hematite in thin section

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sample: FKM-182
locality: Stollberg ore field (possibly the Stollberg mine itself), near Ludvika, Dalarna, Sweden.
rock type: high grade tephroite-hematite-rhodochrosite metasomatite. Some might call this sample a “skarn”, but I prefer to use that term specifically for a calc-silicate rock derived from metasomatism by an adjacent de-volatilizing crystallizing magma. In contrast, this rock isn’t quite “calc”, per se (with Mn > Ca), and also it may likely be a metamorphosed and metasomatized Mn-Fe exhalite with perhaps only an indirect relationship to magmatism (for example, as a heat source to drive hydrothermal fluid circulation).
major mineralogy: The rock is composed of roughly equal parts carbonate, oxide, and silicate. Small quantities of sulfides (pyrrhotite, chalcopyrite, galena and sphalerite) and fluorapatite are also present. The oxide is hematite with a small Mn component. The carbonate occurs as three distinct phases: a coarsely crystalline high-Ca rhodochrosite (which appears as the nearly colorless material in the unpolarized light scanned image) and an intimate mixture of kutnohorite and high-(Mg+Fe) rhodochrosite (these latter two carbonates are finer-grained and slightly more grayish-colored in the unpolarized light scanned image). The abundant “shattered” material in the images is “knebelite” (= a mixed Mg+Fe-rich Mn-dominant olivine [tephroite]). This material is similar to that in FKM-48 but is Fe2+ > Mg and is also Zn-free. As discussed in greater detail with respect to the tephroite in FKM-48, in this case as well the Mn2+ content is only roughly 1 apfu, so it is possible there is significant ordering of Mn2+ into the slightly larger M2 site and Mg+Fe into the slightly smaller M1 site. If this is the case, the “knebelite” in this sample, as with the material in FKM-48, may be a new ordered olivine rather than tephroite sensu strictu. The light brown material in the scanned image is a hydrous Mn-Mg-Fe silicate of varying Mn and Mg content and is a bit challenging to identify due to its fine-grained nature. Based on the optical properties of slightly coarser zones and the Si=4 normalizations, the material is most likely an Mn-rich member of the serpentine family (=caryopilite). Other less likely possibilities include a member of the chlorite family (=gonyerite) or pyrosmalite-(Mn). All three species are prevalent in many of the central Sweden Mn deposits.

mineral representative mineral compositions in FKM-182
galena not analyzed
sphalerite not analyzed
pyrrhotite Fe0.88S1.00
chalcopyrite Cu1.00Fe1.00S2.00
hematite (Fe3+1.94Mn3+0.04Al0.02)O3
rhodochrosite (most Mg+Fe-rich) (Mn2+0.49Mg0.24Fe2+0.20Ca0.07)[CO3]
rhodochrosite (most Ca-rich) (Mn2+0.45Ca0.28Mg0.19Fe2+0.08)[CO3]
kutnohorite (Ca0.84Mn2+0.16)(Mn2+0.56Mg0.34Fe2+0.10)[CO3]2
fluorapatite (Ca4.90Mn2+0.07Fe2+0.02)[P3.00O12](F0.86[OH]0.11Cl0.03)
“MnFe2+[SiO4]” olivine
(most Mn-rich; historically tephroite)
Mn2+1.00(Fe2+0.66Mn2+0.25Mg0.08Fe3+0.01)[Si0.99Fe3+0.01O4]
“MnFe2+[SiO4]” olivine
(most Mg-rich; historically tephroite)
(Mn2+0.92Mg0.08)(Fe2+0.72Mg0.27Fe3+0.01)[Si0.99Fe3+0.01O4]
caryopilite? (Mn2+2.28Mg1.50Fe2+~0.94Fe3+~0.85Al0.010.43)[Si4.00O10]([OH]7.97Cl0.03)
“Mg-caryopilite”? Ca0.01(Mg1.87Mn2+1.63Fe3+~1.49Fe2+~0.14Al0.070.79)[Si4.00O10]([OH]7.97F0.02Cl0.01)

 



Fuka mine Japan hillebrandtite and spurrite in thin sectionFuka mine Japan hillebrandtite and spurrite in thin section

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sample: FKM-183
locality: Fuka mine, Fuka, Bicchi-cho, Takahashi City, Okayama prefecture, Japan.
rock type: add rock type.
major mineralogy: specimen acquired for hillebrandtite and spurrite.

 



Edenville New York warwickite marble in thin sectionEdenville New York warwickite marble in thin section

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sample: FKM-184
locality: Edenville, near Warwick, Orange Co., NY, USA.
rock type: warwickite-forsterite-spinel-clinohumite marble. Granulite facies meta-siliceous dolostone (the boron and fluorine may be of metasomatic origin?)
major mineralogy: The sample is a magnesian marble, but with calcite > dolomite (likely due in part to the combination of dolomite-consuming + calcite-forming reactions to produce metamorphic Mg minerals). These Mg minerals include scattered spinel and relict forsterite “cores”, the latter largely replaced by clinohumite. The normalizations of both the forsterite and clinohumite suggest slight Si deficiencies in their “T” sites; small amounts of boron (~0.28 wt% B) were added to both minerals to improve their site occupancies and analytical totals. See the discussion under sample FKM-8 for more detail about the normalization scheme used for the humite group minerals, and the rationale for estimating possible boron in humite group minerals and olivine from B-rich Franklin marble assemblages. Warwickite (with 1400 ppm Zr) is the boron phase present in this sample. The warwickite shows incipient alteration along fractures to numerous tiny ilmenite grains (too small to give a good analysis), although larger discrete masses of ilmenite are also present. Sparse zirconolite is associated with the larger ilmenite; zirconolite occurrences in marble are not widely reported, so this occurrence is notable. Some special zirconolite composition and normalization features to note: HREE were estimated by an approximate linear extrapolation of the chondrite-normalized REE plot of measured L+MREE. Mg in zirconolite was presently overlooked and has been estimated here to improve the site occupancies and overall analytical total; the actual concentration of Mg, as well as the concentrations of a few additional potentially key elements (e.g. Sc) will be verified at the next opportunity and then updated here. The zirconolite normalization is based on 4 cations. However, charge balancing to the conventional 7[O] anion content did not yield satisfactory results. This suggests that the zirconolite may be partially hydrated due to radiation damage (for example, Blatt et al., 1987 propose that non-measured water accounts for their low analytical totals in high-actinide zones of zirconolite from Malawi). To account for this possibility, the zirconolite normalization allowed up to 1[O] to be replaced with 1[OH] (hence akin to a pyrochlore composition), with concomitant flexibility in assigning an M3+/∑M ratio (M = Fe+Mn) between 0 and 1. A value of M3+/∑M = 0.5 was assumed here, yielding the estimated [OH] content shown in the composition table below. Although this approach allows an estimate of the valences of Fe and Mn, Fe and Mn were reported as FeT and MnT, respectively, to emphasize the high uncertainty in this calculation in light of the present need to estimate some element concentrations. Rounding out the thin section mineralogy is a mass of talc on one side of the sample (presumably after a pre-existing Mg silicate), and veinlets of clinochlore cutting the clinohumite/forsterite crystals. Samples FKM-8, FKM-36 and FKM-112 are also examples of Franklin marble exposures from the adjoining Orange Co., NY/Sussex Co., NJ area containing humite group minerals. Sample FKM-37, also from the Franklin marble, is another B-bearing sample [with fluoborite].
accompanying videos: Short videos featuring the mineral associations and optical properties of the warwickite and clinohumite in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-184
spinel (Mg0.83Fe2+0.16Zn0.01)Al1.99O4
ilmenite (Fe2+0.73Mg0.21Mn2+0.04Ti0.01Ca0.01)Ti1.00O3
zirconolite (Ca0.46Y0.14U0.14[HREE]~0.13Th0.07Nd0.03Gd0.02Ce0.01Sm0.01)(Zr0.82Ti0.17Hf~0.01)
(Ti1.24FeT0.44Mg~0.27MnT0.02Nb0.01)(O~6.52[OH]~0.48)
calcite (Ca0.97Mg0.03)[CO3]
dolomite Ca1.00(Mg0.97Fe2+0.44)[CO3]2
warwickite (Mg1.24Ti0.33Al0.19Fe2+0.13Fe3+0.10V0.01)(O0.96F0.04)[BO3]
forsterite Mg1.00(Mg0.85Fe2+0.13Fe3+0.01)[Si0.96B0.04O3.98F0.02]
clinohumite 4{(Mg1.885Fe2+0.113Mn2+0.005)[Si0.955B0.045O3.955(OH)0.045]} . (Mg0.89Ti0.10Fe3+0.01)(F1.10[OH]0.69O0.21)
talc (Mg2.73FeT0.220.05)[Si3.99Al0.01O10]([OH]1.86F0.13)
clinochlore (Mg4.56Al1.14FeT0.18V0.010.11)[Si2.90Al1.09O10]([OH]7.88F0.11)

 



Falotta Switzerland tinzenite in thin sectionFalotta Switzerland tinzenite in thin section

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sample: FKM-185
locality: Falotta, Tinzen, Switzerland.
rock type: tinzenite-quartz metasomatite. The origin of this rock is presumably related to seafloor hydrothermal Mn deposition that was later modified by high grade metamorphism and accompanying metasomatism. This sample comes from ~12 km E of sample FKM-201, which is from the Schmorrasgrat-Süd mine in the Starlera area.
major mineralogy: The specimen consists of sub-equal amounts of quartz and an axinite-group mineral (tinzenite) dominated by a composition close to the tinzenite-manganaxinite nomenclature boundary. The tinzenite is variably weakly zoned, with scattered zones both more Mn-rich and more Ca-rich (so manganaxinite in places) than the main composition. The B content of the axinite was not analyzed, but was estimated to bring the overall analytical total as close to 100% as possible without exceeding one B apfu in the “B” site (although in a few analyses, a small amount of additional B [up to ~0.05 apfu B] was also allowed to make up for a slight deficiency of Si in the disilicate group). Small patches of tiny hematite crystals are scattered in the thin section, and in one of these clusters sparse tiny arsenoflorencite-(Ce) is present. This appears to be the first observation of arsenoflorencite-(Ce) at Falotta, although the mineral is reported from the nearby (~3.7 km) Parsettens Alp occurrence. Other minerals in this sample are scattered small fluorapatite and titanite in the tinzenite, and sparse tiny monazite in the quartz.
accompanying videos: Short videos featuring the mineral associations and optical properties of the tinzenite in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-185
hematite (Fe3+1.93Ti0.04Mn2+0.02)O3
fluorapatite (Ca4.96Mn2+0.02Sr0.01)[P0.997As0.003O4]3(F0.89[OH]0.11)
monazite-(Ce) (Ce0.36La0.15Nd0.15Y0.09Th0.08Ca0.06Pr0.04Sm0.03Gd0.03[HREE]0.01Pb0.01)[P1.01O4]
arsenoflorencite-(Ce) (Ce0.57Sr0.16La0.15Nd0.10Pr0.04Sm0.01)Al3.00
{[As0.90V5+0.05P0.02S0.02O4][As1.00O3.84(OH)0.16]}([OH]5.98F0.02)
titanite (Ca1.00Mn2+0.01)(Ti0.93Al0.03Fe3+0.01V4+0.01)(O0.92[OH]0.06F0.02)[Si0.98Al0.02O4]
tinzenite-dominant axinite ss
(most Mn-rich; highest z)
(Ca1.23Mn2+0.77)(Mn2+0.94Mg0.03Mn3+0.03)(Al1.92Fe3+0.08)
{[B0.99Al0.01]O[Si3.97Al0.03O14]}([OH]0.99F0.01)
tinzenite-dominant axinite ss
(most Fe-rich; main mod z)
(Ca1.46Mn2+0.53)(Mn2+0.93Mg0.03Fe3+0.03Mn3+0.01)(Al1.89Fe3+0.11)
{[B1.00]O[Si3.95B0.05O14]}(OH)1.00
manganaxinite-dominant axinite ss
(most Ca-rich; lowest z)
(Ca1.74Mn2+0.26)(Mn2+0.96Mg0.02Mn3+0.01Ti0.01)(Al1.92Fe3+0.06Mn3+0.02)
{[B1.00]O[Si3.97Al0.03O14]}(OH)1.00
quartz not analyzed

 



Kuntá Hora Czech Republic anthophyllite in thin sectionKuntá Hora Czech Republic anthophyllite in thin section

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sample: FKM-186
locality: Malešov, Kuntá Hora, Czech Republic.
rock type: hornblende-biotite-anthophyllite schist. Greenschist facies metamorphosed and K-metasomatized meta-serpentinite (derived from a peridotite protolith).
major mineralogy: The rock is predominately anthophyllite with subordinate Mg-rich biotite (phlogopite) and magnesio-hornblende. Minor talc is also present. Scattered relict chromite is relatively abundant, as well as lesser amounts of a variety of chalcogenides. These include primarily pentlandite, but also rare Ni-rich cobaltite (alternatively possibly glaucodot or alloclasite), Co-rich gersdorffite, and a single lath of Co-free nickeline. The cobaltite is typically enclosed in pentlandite (and adjacent pentlandite may be slightly Co-enriched), whereas the gersdorffite and lower-Co pentlandite occur randomly in the matrix. The lone observed nickeline was growing alongside a pentlandite grain. Minor thin calcite veining is present in the sample, and sparse fluorapatite and a single tiny uraninite grain were noted. All of the silicates show some enrichment in both Cr and Ni. Note that the reported distributions of Fe2+ and Mg between the VIM and VIIIM sites in the two amphiboles are not known from structural measurements but are instead assumed based only on cation size considerations.
accompanying videos: Short videos featuring the mineral associations and optical properties of the anthophyllite in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-186
pentlandite (most Ni-rich) (Ni4.70Fe4.24Co0.04)S8.01
pentlandite (most Co-rich) (Ni4.63Fe4.24Co0.11)S8.03
nickeline (Ni0.96Fe0.01)(As0.98S0.02)
cobaltite (Co0.54Ni0.37Fe0.07)As0.99S1.02
gersdorffite (Ni0.59Co0.37Fe0.06)As0.98S1.01
chromite (Fe2+0.78Mg0.17Zn0.03Mn2+0.01)(Cr1.68Al0.24Fe3+0.06)O4
calcite (Ca0.92Fe2+0.03Mn2+0.03Mg0.02)[CO3]
fluorapatite (Ca4.97Y0.01Na0.01Fe2+0.01)[P1.00O4]3(F0.66[OH]0.29Cl0.05)
anthophyllite 1.00(Fe2+0.99Mg0.88Ca0.08Mn2+0.04Na0.19)(Mg4.88Fe3+0.10Cr0.01Ni0.01)
[Si7.90Fe3+0.07Al0.03O22]([OH]1.95F0.05)
magnesio-hornblende (K0.010.99)(Ca1.85Fe2+0.12Na0.02Mn2+0.01)(Mg4.71Fe3+0.14Fe2+0.09Cr0.06Ni0.01)
[Si7.81Al0.14Fe3+0.04O22]([OH]1.95F0.05)
talc Na0.01(Mg2.89FeT0.10Ni0.01)[Si3.98Al0.02O10]([OH]1.95F0.05)
phlogopite (K0.85Na0.010.14)(Mg2.71FeT0.19Cr0.06Al0.02Ti0.01Ni0.01)[Si2.99Al1.01O10]([OH]1.83F0.15O0.02)

 



Dehesa California dumortierite in thin sectionDehesa California dumortierite in thin section

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sample: FKM-187
locality: Dehesa, San Diego Co., CA, USA.
rock type: add rock type. Compare this sample to the similar boron-bearing advanced argillic alteration assemblage in sample FKM-61 and FKM-70.
major mineralogy: specimen acquired for dumortierite.

 



Norberg Sweden dollaseite in thin sectionNorberg Sweden dollaseite in thin section

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sample: FKM-188
locality: Norberg area, Västmanland, Sweden (possibly from the Johanna mine or from the Malmkärra mine).
rock type: add rock type.
major mineralogy: Sample is largely composed of dollaseite-(Ce) and tremolite, with subordinate calcite and scattered gadolinite-(Nd) (Nd here is slightly greater than Ce, which is the next most abundant REE. This may be a new species [UPDATE: as of 2016, gadolinite-(Nd) is an approved species]). In one area of the thin section, patchy talc is intergrown with the calcite, and rare small fluorite is also present (also associated with the calcite). Rare tiny magnetite inclusions in the dollaseite-(Ce) are also observed.
accompanying videos: Short videos featuring the mineral associations and optical properties of the dollaseite in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-188
magnetite Fe2+1.00Fe3+2.00O4
fluorite not analyzed
calcite not analyzed
gadolinite-(Nd) (Nd0.60Ce0.55Y0.26Sm0.17Gd0.12La0.12Pr0.10[HREE]0.06Ca0.02)
(Fe2+0.69Mg0.13Ga0.010.17)(Be1.94Si0.06)[Si1.00O4]2(O1.74[OH]0.22F0.03)
dollaseite-(Ce) (Ca0.93Y0.03[HREE]0.01Gd0.01)(Ce0.54La0.30Nd0.14Pr0.05Sm0.01)(Mg0.81Fe3+0.17)
(Al0.97Fe3+0.03)(Mg0.88Fe2+0.10Mn2+0.02)(F0.71O0.28)[Si2.00O7][Si1.01O4](OH)
tremolite (Na0.01K0.010.98)(Ca1.96Na0.04)(Mg4.73Fe2+0.20Al0.05Mn2+0.01)[Si7.98Al0.02O22]([OH]1.32F0.68)
talc (Ca0.04Na0.01)(Mg2.73FeT0.10Al0.010.16)[Si4.03O10]([OH]1.88F0.12)

 



Isle of Mull Scotland mullite and corundum in thin sectionIsle of Mull Scotland mullite and corundum in thin section

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Isle of Mull Scotland mullite and corundum in thin sectionIsle of Mull Scotland mullite and corundum in thin section

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

sample: FKM-189 (two thin sections cut from the same billet are shown here; the upper and lower image pairs represent samples FKM-189-1 and FKM-189-2, respectively; the analyses reported here are from FKM-189-2).
locality: Loch Scridain area, Isle of Mull, Scotland, UK.
rock type: mullite-corundum-sanidine (partially glass?; buchite?) hornfels. Sanidinite facies pelitic xenoliths in basalt.
major mineralogy: specimen acquired for mullite and corundum. Scattered oxide grains originally thought to be pseudobrookite or ülvospinel turned out to be an Al-dominant armalcolite roughly corresponding to 36 mol% Al2TiO5, 29 mol% Fe2+Ti2O5 (“ferropseudobrookite”), 28 mol% MgTi2O5 (armalcolite) and 7 mol% Fe3+2TiO5 (pseudobrookite); here minor V and Zr were lumped together with Al and Ti, respectively. Similar material has been described from buchite xenoliths associated with the basalt on Disko Island, Greenland (Pedersen, 1979 [← subscription required]). Pedersen’s assignment of armalcolite-group end-members left a small excess of Ti, and he suggested that excess indicated a small component of Ti3+2TiO5 (“anosovite”) was present in the Al-rich armalcolite from Disko Island. This interpretation seems reasonable, since carbonaceous matter in the shale contributed to the formation of other very reduced minerals such as native Fe and cohenite at that locality. In contrast, however, the Al-rich armalcolite in this Isle of Mull sample shows no stoichiometric indication that Ti3+ would need to be present.

mineral representative mineral compositions in FKM-189-2
corundum (Al1.99Fe3+0.01)O3
ilmenite (Fe2+0.85Mg0.12Mn2+0.01Fe3+0.01)(Ti0.98V0.01Fe3+0.01)O3
spinel (Mg0.56Fe2+0.44)(Al1.96Cr0.02Ti0.01)O4
“Al-armalcolite” (Al0.36Fe2+0.29Mg0.28Fe3+0.07)(Ti1.56Al0.32Fe3+0.07V0.03Zr0.01)O5
rutile (Ti0.96V0.01Zr0.01Nb0.01)O2
mullite (Al3.89Ti0.05Fe3+0.02Mg0.02)O1.71[Si1.41Al0.59O8]
cordierite normalization pending
sanidine (most K-rich) (K0.89Na0.02Ba0.01)[Si2.97Al1.03O8]
sanidine (most Na-rich) (Na0.48K0.40Ca0.07)[Si2.93Al1.06P0.02O8]
“andesine”-dominant plag ss (Na0.60Ca0.25K0.12)[Si2.71Al1.28P0.01O8]
“labradorite”-dominant plag ss (Ca0.58Na0.38K0.02)[Si2.38Al1.61O8]

 



Nippyo mine Japan proto-ferro-suenoite in thin sectionNippyo mine Japan proto-ferro-suenoite in thin section

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sample: FKM-190
locality: Nippyo mine, Awano, Kanuma City, Tochigi Prefecture, Honshu Island, Japan.
rock type: spessartine-[proto-ferro-suenoite]-rhodochrosite-pyroxmangite metasomatite. The rocks at the locality are described as “metasedimentary Mn-rich pods in chert country rock”, suggestive of a metamorphosed (contact?) Mn-rich seafloor exhalite.
major mineralogy: specimen acquired for “proto-ferro-mangano-anthophyllite” (which differs in prefix order from the original descriptions, but in any case has been since renamed as proto-ferro-suenoite), pyroxmangite and pyrophanite. Fe-rich pyroxmangite dominates the sample as large crystals (some weakly zoned), veined with rhodochrosite and pyrosmalite-(Mn). Additional rhodochrosite and pyrosmalite occur throughout the sample, and one small grain of the latter was sufficiently Fe-rich to classify as pyrosmalite-(Fe). Clots of strongly colored matted proto-ferro-suenoite (formerly “protomangano-ferroanthophyllite”) are prevalent in the sample; some of the coarser blades show weak zoning. Scattered spessartine garnet occurs in the carbonate and in quartz that is primarily associated with the amphibole. In addition to some coarse core-rim zoning, some of the larger spessartines are finely-included, and these garnets differ somewhat in composition from the smaller ones (see below). Scattered small (10-20 μm) Mn-bearing fluorapatite with orange cathodoluminescence are also most prevalent in the [garnet+quartz+amphibole]-rich portions of the sample. Sparse W-bearing pyrophanite (with up to 1.68 wt% W) is scatttered throughout the sample (however in one instance, the observed MTiO3 phase is instead a W-free but slightly Nb-bearing [1100 ppm Nb] near-(Fe/Mn)-boundary composition ilmenite). A cursory exploration for high z phases found minor pyrrhotite, one small Fe+Co-bearing gersdorffite grain, one small Ni-rich cobaltite grain (suggesting additional compositions spanning the gersdorffite-cobaltite series may be present), one small Fe-rich sphalerite grain, and one small hübnerite grain. Note that the quality of the analyses for these high-z accessory phases is somewhat limited by their extremely small sizes and the possibility of beam overlap with their host silicate. Also, as discussed in the description for similar sample FKM-94, the site occupancies assigned for the pyroxmangite analyses here have not been verified by structural analyses, but are intended only to present consistent formulas from sample to sample to facilitate compositional comparisons.
accompanying videos: Short videos featuring the mineral associations and optical properties of the pyroxmangite, proto-ferro-suenoite and pyrosmalite-(Mn) in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-190
pyrrhotite (Fe0.94)S1.00
sphalerite (Zn0.87Fe0.14)S0.99
gersdorffite (Ni0.57Fe0.25Co0.21)(As0.98Sb0.02)(S0.90As0.07)
cobaltite (Co0.44Ni0.40Fe0.16)(As0.98Sb0.01Bi0.01)(S0.95As0.04)
pyrophanite (Mn2+0.65Fe2+0.31Fe3+0.04)(Ti0.98W0.01Fe3+0.01)O3
ilmenite (Fe2+0.52Mn2+0.48)Ti1.00O3
rhodochrosite (Mn2+0.63Fe2+0.24Ca0.09Mg0.04)[CO3]
fluorapatite (Ca4.84Mn2+0.11FeT0.02Sr0.01Na0.01Ce0.01)[P0.993Si0.007O4]3(F0.81[OH]0.16Cl0.03)
hübnerite (Mn2+0.92Fe2+0.08)[W1.00O4]
spessartine (small; core;
most Mg+Fe-rich)
(Mn2+2.00Fe2+0.64Mg0.27Ca0.09)(Al1.97Fe3+0.03)[Si0.977Al0.02O4]3
spessartine (small; rim) (Mn2+2.08Fe2+0.61Ca0.26Mg0.05)(Al1.96Fe3+0.02Ti0.01)[Si0.987Al0.013O4]3
spessartine (large; included
core; most Ca-rich)
(Mn2+2.04Fe2+0.45Ca0.39Mg0.12)(Al1.97Fe3+0.02Ti0.01)[Si0.983Al0.017O4]3
spessartine (large;
rim; most Mn-rich)
(Mn2+2.53Fe2+0.27Ca0.15Mg0.05)(Al1.94Fe3+0.03Ti0.02)[Si0.983Al0.017O4]3
pyroxmangite (main;
more Ca+Fe-rich)
(Mn2+0.60Ca0.40)Mn2+1.00Mn2+1.00Mn2+1.00(Fe2+0.74Mn2+0.25)Fe2+1.00(Fe2+0.48Mg0.45Fe3+0.07)
[Si6.92Fe3+0.07Al0.01O21]
pyroxmangite (minor
lower z; most Mg-rich)
(Mn2+0.73Ca0.27)Mn2+1.00Mn2+1.00Mn2+1.00(Fe2+0.66Mn2+0.34)Fe2+1.00(Mg0.81Fe2+0.15Fe3+0.03Zn0.01)
[Si6.97Fe3+0.03O21]
proto-ferro-suenoite
(main; most Mg-rich)
1.00(Mn2+1.60Fe2+0.34Na0.04Ca0.02)(Fe2+3.49Mg1.39Fe3+0.10Zn0.010.01?)[Si7.94Al0.06O22]([OH]1.98F0.01)
proto-ferro-suenoite
(higher z patches;
most Mn-rich)
1.00(Mn2+1.94Fe2+0.03Ca0.02Na0.01)(Fe2+3.88Mg0.78Fe3+0.23Zn0.010.09?)[Si7.95Al0.05O22]([OH]1.97F0.03)
pyrosmalite-(Mn) (Mn2+4.06Fe2+3.62Mg0.15Fe3+0.06Al0.04Ca0.010.06)[Si6.00O15]([OH]8.71Cl1.29)
pyrosmalite-(Fe) (Fe2+3.44Mn2+3.37Fe3+0.57Mg0.28Al0.03Ca0.010.30)[Si6.00O15]([OH]9.15Cl0.85)

 



Madagascar hibonite in thin sectionMadagascar hibonite in thin section

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sample: FKM-191
locality: Andrakaholo, Anosy region, Tuléar province, Malagasy Republic.
rock type: spinel-hibonite-corundum-anorthite granulite. The protolith was likely an argillaceous carbonate.
major mineralogy: The sample is composed primarily of near end-member anorthite. Porphyroblasts of corundum are abundant (and are loaded with several types of fluid ± solid inclusions), along with scattered large porphyroblasts of spinel and hibonite. The hibonite is patchy zoned in REE. Minor calcite and baddeleyite, rare phlogopite, and a single thorianite crystal are also present. Within one baddeleyite is also a single small crystal of zirconolite. This sample bears some similarity to FKM-205 and comes from the same vicinity in Madagascar.
accompanying videos: Short videos featuring the mineral associations and optical properties of the baddeleyite, spinel and hibonite in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-191
spinel (Mg0.87Fe2+0.13)Al2.00O4
corundum Al2.00O3
baddeleyite not analyzed
thorianite not analyzed
hibonite (most REE-rich) (Ca0.64Ce0.18La0.12Sr0.02Nd0.01Pr0.01Th0.01)(Al10.94Mg0.61Ti0.29Fe2+0.08Fe3+0.04Si0.04)O19
hibonite (most Ti-rich) (Ca0.97Sr0.02Na0.01Ce0.01Nd0.01Th0.01)(Al10.59Ti0.62Mg0.57Fe2+0.12Si0.05Fe3+0.02)O19
zirconolite (Ca0.67Y0.09U0.09Th0.06[HREE]0.04Gd0.01Sm0.01Nd0.01Ce0.01)
Zr1.00(Ti1.41Al0.19Zr0.17Fe2+0.15Nb0.04Hf0.01V0.01)O7
calcite not analyzed
fluorapatite (Ca4.97Y0.01Ce0.01Nd0.01)[P0.977Si0.013O4]3(F0.98[OH]0.01Cl0.01)
phlogopite (K0.89Na0.06Ba0.020.03)(Mg2.74Al0.17FeT0.05Ti0.03)[Si2.81Al1.19O10]([OH]1.10F0.84O0.07)
anorthite (Ca0.98Na0.01)[Al2.02Si1.98O8]

 



Arkansas wollastonite in thin sectionArkansas wollastonite in thin section

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sample: FKM-192
locality: Union Carbide Mine, Wilson Springs (Potash Sulfur Springs), Garland Co., Arkansas, USA.
rock type: add rock type.
major mineralogy: specimen acquired for wollastonite (and aegirine seems present as well).

 



Långban Sweden cymrite in thin sectionLångban Sweden cymrite in thin section

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sample: FKM-193
locality: Långban, Filipstad, Värmland, Sweden.
rock type: add rock type.
major mineralogy: specimen acquired for cymrite. This sample is mineralogically very similar to FKM-86, also from Långban, and also contains melanotekite and phlogopite.
accompanying videos: Short videos featuring the mineral associations and optical properties of the phlogopite in this thin section offer a more detailed look at this sample.

 



Abtenau Austria crossite in thin sectionAbtenau Austria crossite in thin section

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sample: FKM-194
locality: Webing, near Abtenau, Salzburg, Austria.
rock type: add rock type.
major mineralogy: specimen acquired for crossite.
accompanying videos: Short videos featuring the mineral associations and optical properties of the glaucophane in this thin section offer a more detailed look at this sample.

 



Sunnyside mine Colorado pyroxmangite in thin sectionSunnyside mine Colorado pyroxmangite in thin section

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sample: FKM-195
locality: Sunnyside mine, Silverton, CO, USA.
rock type: add rock type.
major mineralogy: specimen acquired for pyroxmangite.
accompanying videos: Short videos featuring the mineral associations and optical properties of the pyroxmangite in this thin section offer a more detailed look at this sample.

 



Namibia cassiterite tin granite in thin sectionNamibia cassiterite tin granite in thin section

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sample: FKM-196
locality: unspecified locality in Namibia.
rock type: cassiterite-bearing granite.
major mineralogy: specimen acquired for cassiterite.

 



Tasmania stichtite and serpentine in thin sectionTasmania stichtite and serpentine in thin section

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sample: FKM-197
locality: southwestern Tasmania, Australia, possibly from the BHP prospect, Birches Inlet, Macquarie Harbour locality.
rock type: add rock type.
major mineralogy: specimen acquired for stichtite and serpentine.
accompanying videos: Short videos featuring the mineral associations and optical properties of the stichtite in this thin section offer a more detailed look at this sample.

 



Greenwood Maine tourmaline and lepidolite in thin sectionGreenwood Maine tourmaline and lepidolite in thin section

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sample: FKM-198
locality: Black Mountain, Greenwood, Oxford Co., Maine, USA.
rock type: add rock type.
major mineralogy: specimen acquired for elbaite and lepidolite.

 



Namibia shattuckite in thin sectionNamibia shattuckite in thin section

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sample: FKM-199
locality: Kaokoveld Plateau, Kunene region, Namibia.
rock type: add rock type.
major mineralogy: specimen acquired for shattuckite.

 



Red Cloud mine New Mexico bastnasite and fluorite in thin sectionRed Cloud mine New Mexico bastnasite and fluorite in thin section

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sample: FKM-200
locality: Red Cloud Fluorite mine, Gallinas Mts, Red Cloud District, Lincoln Co., New Mexico, USA.
rock type: add rock type.
major mineralogy: specimen acquired for bastnasite-(Ce) and fluorite.

 



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