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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left image: plane-polarized light (E-W); right image: under crossed polarizers; use slider in center to view more of either image
sample: FKM-426 (dealer sample number 8221)
locality: Akhmatovskaya Kop’ (Achmatovsk Mine), Nazyamskie Mountains, Zlatoust, Chelyabinsk Oblast, Russia.
rock type: test.
major mineralogy: The specimen was acquired for ludwigite.
| mineral | representative mineral compositions in FKM-426 |
|---|---|
| magnetite | (Fe2+0.85Mg0.14Mn2+0.01)Fe3+2.00O4 |
| calcite | (Ca0.97Mg0.03)[CO3] |
| dolomite | Ca1.00(Mg0.98Ca0.01)[CO3]2 |
| ludwigite | (Mg1.68Fe2+0.31Ca0.01)(Fe3+0.97Al0.01Fe2+0.01)O2.00[BO3] |
| “hydroxylhumite” | 3{(Mg1.997Mn2+0.003)[Si0.987B0.013O4]} . (Mg0.91FeT0.07Ti0.02)([OH]1.56F0.44O0.04) |
| clinochlore | (Mg4.60Al1.26FeT0.11□0.03)[Si2.78Al1.22O10](OH)8.00 |
accompanying videos: Short videos featuring the mineral associations and optical properties of the ludwigite and “hydroxylhumite” in this thin section offer a more detailed look at this sample.
| mineral | PPL (lower polar rotation) |
PPL (stage rotation) |
XP (stage rotation) |
optic figure (stage rotation) |
|---|---|---|---|---|
| ludwigite PPL: essentially opaque, with dark green visible on thin edges, high relief; XP: birefringence masked by near opacity/body color of mineral; with “hydroxylhumite” and dolomite |
presumably B(+) but crystals were too dark to obtain an optic figure |
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| “hydroxylhumite” PPL: very weak near-colorless/very pale yellow pleochroism, moderate-high relief; XP: up to 2nd order blue δ; with dolomite |
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left image: plane-polarized light (E-W); right image: under crossed polarizers; use slider in center to view more of either image
sample: FKM-427
locality: La Fossa crater, Vulcano Island, Lipari, Sicily, Italy.
rock type: test.
major mineralogy: The specimen was acquired for vonsenite.
left image: plane-polarized light (E-W); right image: under crossed polarizers; use slider in center to view more of either image
sample: FKM-428
locality: The dealer only gave the locality as “Kunene region, Namibia”, but the sample is presumably more specifically from the open pit Sodalite mine near Orotumba, well-known for decorative/lapidary sodalite.
rock type: carbonatite-associated fenite.
major mineralogy: The specimen was acquired for sodalite.
left image: plane-polarized light (E-W); right image: under crossed polarizers; use slider in center to view more of either image
sample: FKM-429
locality: Limberg quarry, Pargas, Finland
rock type: test.
major mineralogy: The specimen was acquired for pargasite, diopside, calcite and meionite.
left image: plane-polarized light (E-W); right image: under crossed polarizers; use slider in center to view more of either image
sample: FKM-430 (dealer sample number 4032)
locality: Dara-i-Pioz Massif, Tajikistan.
rock type: test.
major mineralogy: The specimen was acquired for kupletskite-(Cs).
| mineral | representative mineral compositions in FKM-430 |
|---|---|
| titanite | |
| stillwellite-(Ce) | |
| car (most [Ce+M2+]-rich) | |
| car (most [Y+Er]-rich) | |
| osumilite group 1 | |
| osumilite group 2 | |
| aegirine (most [Ca+Mn]-rich) |
|
| aegirine (most [Na+Fe]-rich) |
|
| “mangano-ferri-fluoro-leakeite” | (Na0.62K0.38)(Na1.89Ca0.11){(Mn2+0.60Mg0.50Zn0.34Fe2+0.32Ti0.19Na0.05)(Fe3+1.96Al0.04)Li1.00} [Si7.92Al0.08O22](F0.84[OH]0.77O0.39) |
| kupletskite-(Cs) (patchy most Ti-rich) |
|
| kupletskite-(Cs) (patchy most Nb-rich) |
|
| leucosphenite | |
| polylithionite | (K0.94Na0.01□0.05)(Li1.86Al0.86Ti0.12FeT0.04Mg0.01Zn0.01Nb0.01□0.10)[Si3.96Al0.04O10]F2.00 |
| microcline | (K0.96Na0.04)[Si2.98Al1.01Fe3+0.01O8] |
| albite | Na0.99[Si2.97Al1.02Fe3+0.01O8] |
| maleevite | (Ba0.99Pb0.01)[B2.00Si1.99Al0.01O8] |
| quartz | not analyzed |
accompanying videos: Short videos featuring the mineral associations and optical properties of the sogdianite-sugilite join ss (osumilite group), aegirine, kupletskite-(Cs), “mangano-ferri-fluoro-leakeite”, leucosphenite and polylithionite in this thin section offer a more detailed look at this sample.
| mineral | PPL (lower polar rotation) |
PPL (stage rotation) |
XP (stage rotation) |
optic figure (stage rotation) |
|---|---|---|---|---|
| sogdianite-sugilite join ss PPL: near colorless, moderate relief; XP: up to 1st order dark gray δ; with aegirine, albite and quartz |
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| aegirine PPL: medium-dark yellow-green/medium dark green pleochroism, high relief; XP: up to 2nd order pink δ; with alkali feldspar and quartz |
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| kupletskite-(Cs) PPL: pale/medium yellow pleochroism, high relief; XP: up to 2nd order green δ; with leucosphenite |
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| “mangano-ferri-fluoro-leakeite” PPL: medium yellowish-green/medium-dark bluish-green pleochroism, high relief; XP: up to 1st order orange-red δ; with aegirine (200X) |
single grain identified was not oriented to give a useful figure | |||
| leucosphenite PPL: near colorless to very pale brown, moderate-high relief; XP: up to 2nd order pink δ; with primarily quartz and alkali feldspar |
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| polylithionite PPL: near colorless, moderate-low to moderate relief; XP: up to 2nd order green-blue δ; with quartz and alkali feldspar |
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left image: plane-polarized light (E-W); right image: under crossed polarizers; use slider in center to view more of either image
sample: FKM-431 (dealer sample number 8207)
locality: Dara-i-Pioz Massif, Tajikistan.
rock type: test.
major mineralogy: The specimen was acquired for leucosphenite.
accompanying videos: Short videos featuring the mineral associations and optical properties of the “ferro-ferri-leakeite”/ferri-fluoro-leakeite and maleevite in this thin section offer a more detailed look at this sample.
| mineral | PPL (lower polar rotation) |
PPL (stage rotation) |
XP (stage rotation) |
optic figure (stage rotation) |
|---|---|---|---|---|
| “ferro-ferri-leakeite”/ferri-fluoro-leakeite PPL: medium-pale yellow-tan/dark green/dark bluish-green pleochroism, high relief; XP: up to 1st order orange-red δ; with aegirine-augite and quartz NOTE: the optic figure video shows two optic axis figures, which differ somewhat in 2V° and notably in intensity of dispersion; presumably these correspond to different compositional zones within the composite crystals. |
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| maleevite PPL: colorless, moderate-high relief; XP: up to 1st order white/pale straw yellow δ; with aegirine-augite, leucosphenite, alkali feldspar and quartz |
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left image: plane-polarized light (E-W); right image: under crossed polarizers; use slider in center to view more of either image
sample: FKM-432 (dealer sample number 8820)
locality: Dara-i-Pioz Massif, Tajikistan.
rock type: test.
major mineralogy: The specimen was acquired for sogdianite.
accompanying videos: Short videos featuring the mineral associations and optical properties of the “pyrochlore” group, sogdianite-sugilite join ss (osumilite group), and tadzhikite-(Ce) in this thin section offer a more detailed look at this sample.
| mineral | PPL (lower polar rotation) |
PPL (stage rotation) |
XP (stage rotation) |
optic figure (stage rotation) |
|---|---|---|---|---|
| “pyrochlore” (U-rich; zoned in Ca & Na; F & OH) PPL: variably brown, high relief; XP: isotropic; with sogdianite, albite and quartz (100X + condenser lens) |
isotropic | |||
| sogdianite-sugilite join ss PPL: near colorless, moderate relief; XP: up to 1st order medium gray δ; with aegirine-augite and albite |
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| tadzhikite-(Ce) PPL: weak pale/medium-pale brown pleochroism, high relief; XP: up to 1st order orange δ; with sogdianite and albite |
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left image: plane-polarized light (E-W); right image: under crossed polarizers; use slider in center to view more of either image
sample: FKM-433 (dealer sample number 8139)
locality: Dara-i-Pioz Massif, Tajikistan.
rock type: test.
major mineralogy: The specimen was acquired for sugilite.
accompanying videos: Short videos featuring the mineral associations and optical properties of the [Zr+Ti]-rich sugilite (osumilite group) in this thin section offer a more detailed look at this sample.
| mineral | PPL (lower polar rotation) |
PPL (stage rotation) |
XP (stage rotation) |
optic figure (stage rotation) |
|---|---|---|---|---|
| [Zr+Ti]-rich sugilite PPL: near colorless, moderate relief; XP: up to 1st order dark gray δ; with quartz and minor aegirine and albite |
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left image: plane-polarized light (E-W); right image: under crossed polarizers; use slider in center to view more of either image
sample: FKM-434 (dealer sample number 2872)
locality: Tip Top Mine, Fourmile, Custer Mining District, Custer Co., South Dakota, USA.
rock type: test.
major mineralogy: The specimen was acquired for jahnsite-(CaMnMg) and various Fe-phosphates.
accompanying videos: Short videos featuring the mineral associations and optical properties of the leucophosphite, “ferrisicklerite”, frondelite/Mn-rich rockbridgeite and jahnsite-(CaMnMg) in this thin section offer a more detailed look at this sample.
| mineral | PPL (lower polar rotation) |
PPL (stage rotation) |
XP (stage rotation) |
optic figure (stage rotation) |
|---|---|---|---|---|
| leucophosphite PPL: near colorless to very pale yellowish-tan, high relief; XP: up to 1st order orange-red δ, but with strong anomalous blue overtones in low birefringence sections; with several additional Fe-(Mn)- phosphates |
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| “ferrisicklerite” PPL: orange/red to magenta/dark red/nearly black pleochroism, presumably dependent on degree of alteration to heterosite; high relief; XP: birefringence largely masked by body color of mineral; with frondelite/Mn-rich rockbridgeite and other Fe-(Mn)-phosphates |
no suitable grain was found that gave a useful figure | |||
| frondelite/Mn-rich rockbridgeite PPL: medium-dark orange-yellow/medium-dark orange-red pleochroism, high relief; XP: birefringence largely masked by body color of mineral; with “ferrisicklerite” and other Fe-(Mn)-phosphates |
no suitable grain was found that gave a useful figure | |||
| jahnsite-(CaMnMg) PPL: patchy weak near colorless/pale yellow/medium brownish-yellow pleochroism, moderate to moderate-high relief; XP: up to 1st order orange-red δ (elsewhere in the sample, up to 1st order purple δ), but with anomalous blue overtones in low birefringence sections; with frondelite/Mn-rich rockbridgeite and leucophosphite NOTE: the optic figure video shows a nice example of strong vibration direction dispersion, unique to monoclinic and triclinic crystals. Because the BxA figure is somewhat off-center, it’s not unequivocal whether the observed dispersion is horizontal (b = BxO) or crossed (this is suspected; b = BxA). |
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left image: plane-polarized light (E-W); right image: under crossed polarizers; use slider in center to view more of either image
sample: FKM-435 (dealer sample number 8672)
locality: Jebel Harmun, Quds Governorate, West Bank, Palestine.
rock type: test.
major mineralogy: The specimen was acquired for ternesite and larnite. In hand sample, the specimen consists of scattered large (1-2 mm) rhombic prismatic dark gray crystals within a very fine-grained medium-gray matrix. Optically, under low magnification, the rhombic prisms appear to be poikioblastic single crystals, with relief and birefringence consistent with ternesite; however, under high magnification, the large prisms are revealed to actually be composed of many tiny individual crystals (50 to 100 μm in size), confirmed by EPMA to be ternesite, all aligned in the same optical orientation within an individual large rhombic crystal. Hence, these large rhombic prisms are not individual crystals at all, but appear to be pseudomorphs of ternesite after some pre-existing mineral. Given the prisms’ overall shapes (and in one case what appears to perhaps be a fishtail twin), and the bulk Ca-sulfate-rich composition of the rock, the pre-existing mineral could likely have been gypsum. Under the electron beam, the rhombic crystals are nearly invisible in both SE and BSE imaging, since the matrix also largely consists of tiny ternesite crystals (although randomly oriented). One subtle difference between the fine-grained minerals within the large prisms versus the matrix is the presence of a ellestadite-like phase only within the matrix and not within the pseudomorphs. Otherwise the additional mineralogy is similar: abundant ye’elimite (included with tiny ternesite) is present, along with small widespread spinel and sharyginite, and scattered larnite. The sample also contain rare Ag-bearing djurleite and vorlanite.
accompanying videos: Short videos featuring the mineral associations and optical properties of the ternesite in this thin section offer a more detailed look at this sample.
| mineral | PPL (lower polar rotation) |
PPL (stage rotation) |
XP (stage rotation) |
optic figure (stage rotation) |
|---|---|---|---|---|
| ternesite (pseudomorph after gypsum?) PPL: colorless, moderate-low relief; XP: up to 1st order light gray δ; with primarily larnite, ye’elimite and spinel NOTE: ancillary stage rotation PPL and XP videos at high magnification (500X) show the fine-grained polycrystalline but optically-aligned nature of the ternesite, along with textural detail of the overall very fine-grained mineral assemblage |
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upper left image: plane-polarized light (E-W); upper right image: under crossed polarizers; use slider in center to view more of either image
sample: FKM-436 (dealer sample number 2763)
locality: Jocão claim, Conselheiro Pena, Minas Gerais, Brazil.
rock type: test.
major mineralogy: The specimen was acquired for tavorite and other phosphates.
left image: plane-polarized light (E-W); right image: under crossed polarizers; use slider in center to view more of either image
sample: FKM-437 (dealer sample number 3733)
locality: Jakobsberg Mine, Jakobsberg ore field, Nordmark district, Filipstad, Värmland, Sweden.
rock type: Although not associated with a causative intrusion, and indeed presumably formed by a completely different process, this mineralization style has been commonly referred to as a “Mn skarn”. A better term for this and related occurrences may be “calcareous Mn-metasomatite”. The original Fe and Mn were likely derived from exhalative hydrothermal processes, perhaps akin to those of modern seafloor “black smokers”. While enrichments of some of the associated elements such as As, Sb, Ba and Pb may have been contemporaneous, others such as Be and B were likely introduced later. Subsequent high-grade metamorphism (perhaps accompanied by additional metasomatism) facilitated the redistribution of elements into the diverse and unusual mineral assemblages we observe today.
major mineralogy: The specimen was acquired for margarosanite.
upper left image: plane-polarized light (E-W); upper right image: under crossed polarizers; use slider in center to view more of either image
sample: FKM-438 (dealer sample number 8802)
locality: The level of detail on the specimen label is “Tirodi, Balaghat District, Madhya Pradesh, India”, but presumably the sample is more specifically from the South Tirodi mine.
rock type: test.
major mineralogy: The specimen was acquired for braunite and various Mn-rich amphiboles.
left image: plane-polarized light (E-W); right image: under crossed polarizers; use slider in center to view more of either image
sample: FKM-439 (dealer sample number 8823)
locality: The locality is a drilled unnamed carbonatite stock in the vicinity of Tul’ilukht Bay, Khibiny Massif, Murmansk Oblast, Russia.
rock type: test.
major mineralogy: The specimen was acquired for britholite-(Ce) and calcite.
left image: plane-polarized light (E-W); right image: under crossed polarizers; use slider in center to view more of either image
sample: FKM-440 (dealer sample number 7592)
locality: Km 3 open pit, Lavrion Mining District, Lavreotiki, East Attica, Attica, Greece.
rock type: test.
major mineralogy: The specimen was acquired for gaspéite.
upper left image: plane-polarized light (E-W); upper right image: under crossed polarizers; use slider in center to view more of either image
sample: FKM-441 (dealer sample number 7635)
locality: The locality is an unnamed dumortierite occurrence about 16 km NW of the old Ogilby Southern Pacific Railroad station, Imperial Co., CA, USA.
rock type: test.
major mineralogy: The specimen was acquired for dumortierite, hematite and quartz.
left image: plane-polarized light (E-W); right image: under crossed polarizers; use slider in center to view more of either image
sample: FKM-442 (dealer sample number 3200)
locality: Aris Quarries, Aris, Windhoek Rural, Khomas Region, Namibia.
rock type: test.
major mineralogy: The specimen was acquired for sazhinite-(La) and tuperssuatsiaite.
sample: FKM-443 (billet courtesy of Steven Maliner-Colvin, Iris Metals [Custer, SD, USA])
locality: Corundum Knob, Clay Co., NC, USA.
rock type: corundum-edenite-margarite schist, representing a partially-retrograde assemblage derived from an ophiolite-affiliated originally high-grade (sapphirine-bearing) meta-troctolite.
major mineralogy: The specimen was acquired for margarite, edenite and corundum. There’s some question (as in, “I have a question”) as to whether the amphibole in this assemblage is edenite, or potentially a more Al-rich species such as pargasite.
sample: FKM-444
locality: Daimonjiyama, Kyoto City, Kyoto Prefecture, Japan.
rock type: retrograded sanidinite-facies metapelitic hornfels.
major mineralogy: The specimen was acquired for indialite and cordierite, which in the freshest examples form porphyroblasts of an indialite “flower” with cordierite “petals” (“cherry blossom stone”). However, even the freshest of these “cherry blossoms” are incipiently altered to sericite (±chlorite), and in many cases, the indialite and cordierite have been completely replaced and pseudomorphed by the sericite+chlorite “pinite”, a characteristic alteration style of cordierite.
sample: FKM-445
locality: Norra Kärr, Gränna, Jönköping, Småland, Sweden.
rock type: test.
major mineralogy: The specimen was acquired for fluoro-leakeite. Another similar sample from Norra Kärr, also with fluoro-leakeite, is FKM-175.
sample: FKM-446
locality: Woods mine, Tamworth, Darling Co., NSW, Australia.
rock type: Upper amphibolite facies manganiferous metasediment, with possible superimposed Na-metasomatism?
major mineralogy: The specimen was acquired for mangano-ferri-eckermannite. Sample FKM-30 is a somewhat similar appearing specimen, also from the Woods mine, that had been acquired for “kozûlite” (which was re-defined as mangano-ferri-eckermannite), but was subsequently discovered to be composed of primarily mangano-mangani-ungarettiite.
sample: FKM-447
locality: Crestmore quarries, Crestmore, Riverside Co., CA, USA.
rock type: high grade marble. Contact aureole (high-T low-P; sanidinite(?) facies) metamorphosed siliceous dolostone, with possible additional metasomatic contribution from the causative intrusion.
major mineralogy: The specimen was acquired for merwinite. Several additional Crestmore quarry samples are included here.
sample: FKM-448
locality: Dara-i-Pioz Massif, Tajikistan.
rock type: test.
major mineralogy: The specimen was acquired for hejtmanite and zektzerite.
sample: FKM-449
locality: Dara-i-Pioz Massif, Tajikistan.
rock type: test.
major mineralogy: The specimen was acquired for nalivkinite and zektzerite.
sample: FKM-450
locality: Kovdor massif, Russia.
rock type: test.
major mineralogy: The specimen was acquired for kovdorskite.