samples FKM-326 to FKM-350

 

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

under shortwave ultraviolet [SWUV] illumination

 
sample: FKM-326 (dealer sample number 7010)
locality: Kuh-i-Lal, Pyandzh River Valley, Gorno-Badakhshan, Tajikistan.
rock type: high grade magnesian marble.
major mineralogy: The specimen was acquired for clinohumite and spinel.

 



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

under shortwave ultraviolet [SWUV] illumination

 
sample: FKM-327 (dealer sample number 4290)
locality: Area Novo-Dzhaginskoe deposit, Omsukchan, Ducat District, Kolyma River Basin, Magadan Oblast, Russia. Little appears written in English about the locality, although it is mentioned in passing as a “tin-silver” deposit in the introduction of an Ore Geology Reviews article on the nearby Rogovik deposit (Zhuravkova et al., 2017); that single mention references an article entitled “Geology of silver-complex-metal mineralization of the Novyi Dzhagyn intrusive arched structure” by Kalinin et al., 1984 in the journal Kolyma (in Russian). According to a no longer accessible .kml file, the coordinates for the locality appear to be 62°47’46.1″N 155°25’21.5″E. In an additional compilation reference, Nokleberg et al., 2005 (p. 386; Table 4) lists “Novy Djagyn” as a porphyry Sn deposit at 62°48’N 155°25’E. Similar but less detailed data are also compiled earlier in Nokleberg et al., 1997 (p. 26; deposit # P56-14).
rock type: possibly a metamorphosed B-bearing advanced argillic alteration assemblage associated with a Sn(+Ag) deposit.
major mineralogy: The specimen was acquired for dumortierite.
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.

mineral PPL (lower
polar rotation)
PPL
(stage rotation)
XP
(stage rotation)
optic figure
(stage rotation)
dumortierite
PPL: pinkish-red/near colorless pleochroism, high relief;
XP: up to 1st order red-purple δ;
with tourmaline, quartz and muscovite

 



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

sample: FKM-328
locality: Trikorfo area, Theologos, Thasos, East Macedonia and Thrace, Greece.
rock type: muscovite-viridine-quartz lenses in manganiferous metapelitic gneiss. A recent description of the geology of the locality is given by Voudouris et al., 2016, which also includes mineral composition data complementary to what is (or will be) given here.
major mineralogy: The specimen was acquired for manganian andalusite (“viridine”).
accompanying videos: Short videos featuring the mineral associations and optical properties of the Mn-bearing andalusite (“viridine”) 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)
andalusite (“viridine”)
PPL: greenish-yellow/green/bright yellow pleochroism, high relief;
XP: up to 1st order gray δ, partially masked by body color of mineral and by strong anomalous blue/brown overtones;
with quartz, plagioclase and mica

 



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

sample: FKM-329
locality: Prabornaz mine, Saint-Marcel, Val d’Aosta, Italy.
rock type: test. Blueschist to eclogite facies meta-Mn-rich sediment (distal volcanogenic exhalite?) at peak conditions retrograded to greenschist facies, with superimposed accompanying metasomatism (Tumiati et al., 2010).
major mineralogy: The specimen was acquired for purple manganian omphacite (violane).
accompanying videos: Short videos featuring the mineral associations and optical properties of the omphacite (“violan”) 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)
omphacite (“violan”)
PPL: very weak lavender pleochroism, high relief;
XP: up to 2nd order green δ;
with calcite and very minor piemontite

 



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

sample: FKM-330
locality: Mt. Cavalluccio, Sacrofano Caldera, Campagnano, Rome, Lazio, Italy.
rock type: Pyroclastic flow-related ejectum of feldspathoid-bearing alkali-syenite composition.
major mineralogy: The specimen was acquired for mottanaite-(Ce).

 



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

sample: FKM-331
locality: Cerchiara Mine, Borghetto Vara, Vara Valley, La Spezia Province, Liguria, Italy.
rock type: test.
major mineralogy: The specimen was acquired for namansilite.
accompanying videos: Short videos featuring the mineral associations and optical properties of the namansilite 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)
namansilite
PPL: orange-yellow/deep red/magenta pleochroism, high relief;
XP: birefringence color masked by body color of mineral;
with calcite and minor quartz
presumably B(-)
but no useful optic figure was found

 



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

sample: FKM-332 (billet courtesy of V. King [Rochester, NY])
locality: Lewistown area, Fergus Co., Montana, USA.
rock type: Likely authigenic or metasomatic V-enriched epidote-group mineralization (mukhinite) in or near [so presumably related to] highly-vanadiferous oil shale in the central Montana Mississippian age Heath Formation (reported locally up to ~8000 ppm V2O5; Desborough et al., 1981).
major mineralogy: The specimen was acquired for mukhinite.
accompanying videos: Short videos featuring the mineral associations and optical properties of the mukhinite 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)
mukhinite
PPL: very pale green/moderate reddish-brown pleochroism,
high relief;
XP: up to 2nd order blue-green δ;
with tremolite and possible “chabazite”?

 



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

sample: FKM-333
locality: Aghbar Mine, Bou Azzer District, Ouarzazate Province, Drâa-Tafilalet, Morocco.
rock type: test.
major mineralogy: The specimen was acquired for roselite.

 



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

sample: FKM-334
locality: N’Chwaning II Mine, Kuruman, Kalahari manganese field, Northern Cape, South Africa.
rock type: test.
major mineralogy: The specimen was acquired for manganvesuvianite and hausmannite.
accompanying videos: Short videos featuring the mineral associations and optical properties of the manganvesuvianite 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)
manganvesuvianite
PPL: pale yellow/magenta/red pleochroism, high relief;
XP: up to 1st order red-purple δ, partially masked by body color of mineral and by strong anomalous blue/brown overtones;
open-space filling with opaque hausmannite

 



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

sample: FKM-335
locality: Le Novelle Quarry, Ercolano, Monte Somma, Somma-Vesuvius Complex, Naples, Campania, Italy.
rock type: sanidinite facies metasomatized metacarbonate ejecta.
major mineralogy: The specimen was acquired for marialite, “apatite”, “mica” and calcite.

 



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

sample: FKM-336
locality: Le Coreux, Salmchâteau, Vielsalm, Stavelot Massif, Belgium.
rock type: test.
major mineralogy: The specimen was acquired for kanonaite. It is possible some stavelotite-(La) may be present as well.
accompanying videos: Short videos featuring the mineral associations and optical properties of the kanonaite 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)
kanonaite
PPL: yellow-green/deep bluish-green/deep yellow-orange pleochroism, high relief;
XP: birefringence color masked by body color of mineral;
with muscovite

 



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

sample: FKM-337
locality: Graulay, Hillesheim, Vulkaneifel, Rhineland-Palatinate, Germany.
rock type: late stage cavity filling in nephelinite.
major mineralogy: The specimen was acquired for melilite, nepheline, skeletal perovskite, magnetite and fluorapatite.

 



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

under shortwave ultraviolet [SWUV] illumination

 
sample: FKM-338 (billet courtesy of V. King [Rochester, NY])
locality: Hpakant-Tawmaw jade tract, Kachin state, Burma.
rock type: blueschist to eclogite facies jadeitite.
major mineralogy: The specimen was acquired for chromian epidote.

 



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

sample: FKM-339 (billet from Univ. Arizona petrology collection; sample 7-28-60-15 [the 15th sample added to the collection on 28 July 1960])
locality: The locality is listed as “Ogilby, CA”, although this now-abandoned town likely just represented a convenient nearby road/railroad point-of-access for the mines in the Cargo Muchacho Mountains a few kilometers to the NE. The probable actual locality is on the western edge of the Cargo Muchacho Mountains, from one of the quarry exposures at Vitrefrax Hill/Bluebird Hill, where kyanite was mined for refractory purposes.
rock type: a moderate-grade metamorphosed equivalent of an advanced argillic metasomatic assemblage.
major mineralogy: The specimen was acquired for pyrophyllite, kyanite and lazulite (and/or dumortierite).

 



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

sample: FKM-340 (billet from the Univ. Arizona mineralogy collection; sample was orphaned and subsequently dis-used)
locality: unknown, but presumably from one of the chromite deposits of eastern Turkey that abundantly supplied attractive purple “kämmererite” specimens to the collector market in the 1980s/1990s; possible localities include the Guleman Mines in Elazig Province, or perhaps more likely one of the two more famous mines in the Kop Daglari area in Erzurum Province.
rock type: altered chromatite.
major mineralogy: The specimen was acquired for chromite and chromian clinochlore (“kämmererite”, and/or chromian amesite).

 




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sample: FKM-341
locality: sub-locality #4, at Mautia Hill, Kongwa, Kongwa District, Dodoma Region, Tanzania.
rock type: whiteschist-associated UHP metamorphic rock.
major mineralogy: The specimen was acquired for edenite.

 




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sample: FKM-342
locality: boulder field of ejected volcanic bombs, east of the Ol Doinyo Lengai natrocarbonatite volcano, Ngorongoro District, Arusha region, Tanzania.
rock type: carbonatite-associated combeite-wollastonite nephelinite bombs.
major mineralogy: The specimen was acquired for combeite, wollastonite, nepheline and augite.

 




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sample: FKM-343
locality: White Cloud pegmatite, South Platte, Jefferson Co., CO, USA.
rock type: REE-bearing granite pegmatite.
major mineralogy: The specimen was acquired for thalénite-(Y), yttrofluorite, allanite-(Ce) and bastnäsite-(Ce).

 




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sample: FKM-344 (billet courtesy of B. Widener, Univ. Arizona [thanks for the cool sample, Brandon!])
locality: Gun claim, located 4 km SE of Wilson Lake, 16 km SE of Itsy Mountain and 155 km NE of Ross River, Yukon, Canada.
rock type: test.
major mineralogy: The specimen was acquired for muirite and sanbornite.

 




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sample: FKM-345 (billet courtesy of B. Widener, Univ. Arizona [thanks for the cool sample, Brandon!])
locality: the label states “High Pellice valley, Massif of Monviso, Piedmont Italy”, but this location is a bit problematic because the head of the Pellice Valley is not within the Monviso Massif and at best only abuts its northern margin. Chromian omphacite-bearing jadeitite is well known from Neolithic-age quarries on Monviso (Monte Viso) as a source of “Alpine jade” axeheads and tools, but the online “chatter” among the mineral collector community selling similar material suggests this is a much more recent find. One online dealer specifically describes samples of “chrome-omphacite with gedrite”, and with a “polished surface” (apparently with a polished window is how these new samples are hitting the market), from a new find in the Italian Alps. The locality is denoted as being near Rifugio Barbara Lowrie [~44.75N ~7.08E], Monte Comba Carbonieri area, [~7 km SSW of Bobbio Pellice], Pellice Valley, Piedmont, Italy (note: the bracketed portions above are a few additional geo-locaters I’m including for extra detail). Between the physical description of the material, the location of Rifugio Barbara Lowrie in the “High Pellice Valley”, and the recognition that material from a new find is currently hitting the market, it is strongly believed this sample is indeed from this new Rifugio Barbara Lowrie locality.
rock type: test.
major mineralogy: The specimen was acquired for chromian omphacite/jadeite; if the presumed locality is correct, gedrite has also been reported from this material.

 




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sample: FKM-346
locality: Mont Saint-Hilaire, Montérégie, Québec, Canada.
rock type: nepheline syenite.
major mineralogy: The specimen was acquired for normandite.

 




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sample: FKM-347
locality: from an unspecified locality in the region of Lleida (Lérida), Catalonia, Spain.
rock type: test.
major mineralogy: The specimen was acquired for aerinite.

 




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sample: FKM-348
locality: Gjerdingselva, Nordmarka, Lunner, Oppland, Norway.
rock type: test.
major mineralogy: The specimen was acquired for gagarinite-(Y). Note: gagarinite-(Y) is reportedly decomposed by water, so the thin section was prepared using a non-aqueous fluid.

 




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sample: FKM-349
locality: Bellerberg volcano, Ettringen, Eifel Volcanic Fields, Germany.
rock type: test.
major mineralogy: The specimen was acquired for calcio-olivine and portlandite. Note: portlandite is slightly soluble in water, so the thin section was prepared using a non-aqueous fluid.

 




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sample: FKM-350
locality: Xianghualing Mine, Xianghualing Sn-polymetallic ore field, Linwu Co., Chenzhou, Hunan, China.
rock type: phlogopite-rich greisen-like skarn developed in metamorphosed limestone intruded by granite.
major mineralogy: The specimen was acquired for hsianghualite, phlogopite, and possibly additional rarer Be and Li minerals.

 



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