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sample: FKM-101 (billet from the Univ. Arizona petrology collection, sample Wards 87; this sample is similar to and from the same vicinity as FKM-115)
locality: Chester, Windsor Co., VT, USA.
rock type: talc-chlorite schist. Greenschist facies metabasite.
major mineralogy: Predominately chlorite and talc, with minor apatite and pyrite.

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

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sample: FKM-102 (billet from the Univ. Arizona petrology collection, sample Wards 89)
locality: near Custer, SD, USA.
rock type: microcline-tourmaline-biotite-muscovite schist. Rich in Al, K, (Fe+Mg) and B, but with no chlorite and essentially no quartz or feldspars in the matrix, the mineralogical reflection of the bulk rock chemistry seems unusual for a typical pelitic protolith. It may be possible that the protolith was a metasomatic rock prior to metamorphism, regardless of an original sedimentary or igneous origin.
major mineralogy: The phyllosilicate matrix of this schist is composed of approximately sub-equal amounts of muscovite and Fe-rich biotite. Quartz in the matrix is surprisingly uncommon, and there is no fine-grained plagioclase or K-spar within the matrix. Two distinctive porphyroblast populations are present: metamorphic microcline overgrows scattered “mini-augen” of orthoclase (likely relict), and tourmaline is present oriented both parallel to the long dimension of the thin section and perpendicular to the plane of the thin section (hence appearing to define two roughly perpendicular lineations within the plane of the phyllosilicate foliation). Although the tourmaline exhibits optically distinct rims and cores (the former shows tan to brown pleochroism, while the latter shows grayish-brown to bluish pleochroism), chemical analyses suggest little apparent compositional difference between the cores and rims (however, there possibly may be a significant difference in the Fe2+/Fe3+ ratio; see the below discussion on normalization constraints). Sparse near-end-member albite occurs along the outer edges of a few of the microcline porphyroblasts. Abundant tiny apatite and monazite are scattered in the matrix. For the “core” tourmaline, mathematically permissible values of M3+/∑M (M = Fe+Mn) span from 0.00 to 0.25 (which yield OH/(O+OH) ratios consistent with dravite, but are too Al-rich to normalize to dravite), from 0.25 to 0.33 (which yield OH/(O+OH) ratios consistent with oxy-dravite, but which can not be readily cast into either an oxy-dravite or oxy-schorl formula), and finally from 0.33 to 0.55 (which also yield OH/(O+OH) ratios consistent with oxy-dravite, and can be successfully normalized as such). Values of M3+/∑M above 0.55 are not mathematically permissible, producing non-sensical negative OH/(O+OH) ratios. A similar evaluation can be done for the “rim” tourmaline: in this case, mathematically permissible values of M3+/∑M from 0.00 to 0.18 yield formulas with OH/(O+OH) ratios consistent with dravite and and which can be successfully normalized as such; values between 0.18 and 0.25 also yield OH/(O+OH) ratios consistent with dravite, but simultaneously calculate cation site-fillings more consistent with oxy-dravite; and finally values from 0.25 to 0.44, which yield OH/(O+OH) ratios consistent with oxy-dravite but which again can not be readily cast into either an oxy-dravite or oxy-schorl formula. Analogous to the “core” normalizations, values of M3+/∑M above 0.44 for the “rim” normalizations yield non-sensical negative OH/(O+OH) ratios. The interesting outcome of this calculation is that for the “core” tourmaline, a plausible formula can only be derived for values of M3+/∑M ranging from 0.33 to 0.55 (hence, it must be an oxy-dravite), whereas for the “rim” tourmaline, a plausible formula can only be derived for values of M3+/∑M ranging from 0.00 to 0.18 (hence, it must be a dravite). While this type of calculation is subject to the limitations of analytical error and the challenge of analyzing tourmaline for all components, it is intriguing that the normalization constraints are at least superficially supported by the observed optical property differences (i.e. color in PPL). Nominally, micro-Mössbauer or some other method that can tease out the actual valence states of the Fe (& Mn) in the sample (plus analyses of Li and B and maybe even a structural analysis) are necessary to unequivocally identify these tourmaline species. Still, given the difference in optical properties, however, representative M3+/∑M values of 0.44 (for the “core” composition) and 0.09 (for the “rim” composition) were selected to be close the midpoints of their respective aforementioned successful M3+/∑M ranges, resulting in a different name for each zone. The tourmaline from this sample has been previously analyzed by SIMS (at Arizona State University) for B isotopes: δ11B = -19.3±0.6 ‰. It is not known if the isotopic analysis was done on a core or rim area of the separated crystal.
accompanying videos: Short videos featuring the mineral associations and optical properties of the oxy-dravite in this thin section offer a more detailed look at this sample.

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sample: FKM-103 (billet from Univ. Arizona petrology collection, sample 191-K-3)
locality: Kimberley, Northern Cape province, South Africa.
rock type: kimberlite.
major mineralogy: largely serpentinized forsterite.

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sample: FKM-104
locality: Harding pegmatite, Picuris district, Taos Co., NM, USA.
rock type: mica-rich segregation from Li-Ta pegmatite.
major mineralogy: Orange fluorcalciomicrolite crystals abundantly scattered in a fine-grained pink lithian muscovite, with minor microcline. Rare thin rims of yellow BiVO4 (pucherite?), interstitial to the mica, were verified by EPMA. Interestingly, the specimen was initially labeled as “mimetite in cobaltoan dolomite, from Tsumeb”, and superficially there is a resemblance to that material in hand sample, with lustrous orange/tan crystals in a sugary pink matrix. But note that the crystal morphology of microlite and mimetite are very different(!), and this is further exemplified in thin section by the predictably uniformly isotropic nature of the microlite. Also in thin section, note that mica has a substantially lower birefringence than dolomite. The Li content of the mica is estimated from charge balance and overall analytical total considerations; similarly, a small amount of Rb is assumed in the mica and K-spar from this type of environment, but the Rb contents have not yet been measured. ICP-MS verification of the Li and Rb contents, as well as the determination of other elements potentially present (i.e. B, Cs), is planned.
accompanying videos: Short videos featuring the mineral associations and optical properties of the microlite in this thin section offer a more detailed look at this sample.

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sample: FKM-105 (billet courtesy of C. Loehn, Louisiana Tech University)
locality: “azurite locality”, near K2, Gilgit-Baltistan, Pakistan.
rock type: quartzofeldspathic gneiss. This rock is referred to in the mineral collector & lapidary literature as the “K2 granite”, but the texture is more reminiscent of an orthogneiss.
major mineralogy: This unusual rock contains large (to ~1 cm) nearly spherical bright blue “sunbursts” scattered through the largely quartz+feldspar gneissic matrix (in some hand samples of this material, garnet is also present, but not in the billet from which this thin section was prepared). Muscovite and biotite (~450 ppm Cu), the latter partially altered to chlorite (~1000 ppm Cu), are also present. Although there are indeed small scattered grains of azurite in the “sunbursts”, the bulk of the blue coloration is paler and comes from low z alteration zones in the plagioclase that appear to be a very fine-scale admixture of albite+quartz (calculated at ~70% albite + ~30% quartz at the resolution of the beam, and which contains, in bulk, ~1200 ppm Cu). The nature of this Cu is unclear: whether it is chemically incorporated in the feldspar or quartz, or whether it occurs as sub-micron particles of azurite, chrysocolla or another blue Cu mineral. Overall, the sample shows partial propylitic alteration; in addition to chlorite and the Cu-bearing feldspathic “sunbursts”, there is also minor secondary titanite (~660 ppm Cu) and epidote (not presently analyzed for Cu).

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sample: FKM-106 (billet from Univ. Arizona economic geology collection; sample FEN-5)
locality: Damtjern Lake, Fen complex, Nome, Telemark, Norway.
rock type: “damtjernite”. Lamprophyre associated with the Fen carbonatite.
major mineralogy: test.
accompanying videos: Short videos featuring the mineral associations and optical properties of the spinel in this thin section offer a more detailed look at this sample.

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sample: FKM-107 (billet leftover from FKM M.S. thesis borosilicate calorimetry project; sample 5012)
locality: Mobetsu, Madagascar (note: although this location appears on the mineral dealer label, it has not been located on any examined map of Madagascar).
rock type: test.
major mineralogy: grandidierite.

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sample: FKM-108 (billet leftover from FKM M.S. thesis borosilicate calorimetry project; sample U.S.N.M. 121887 [alternatively NMNH 121887])
locality: Vohibola phlogopite mine, Behara commune, Amboasary district, Tuléar province, Madagascar.
rock type: test.
major mineralogy: grandidierite.
accompanying videos: Short videos featuring the mineral associations and optical properties of the grandidierite in this thin section offer a more detailed look at this sample.

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sample: FKM-109 (billet from Univ. Arizona petrology collection; sample 350:25)
locality: unlabeled, but believed to be from one of the numerous blueschist exposures in Marin or Sonoma Co., CA, USA.
rock type: almandine-lawsonite-glaucophane schist. Blueschist facies metamorphosed mafic rock (basalt or possibly mafic volcaniclastic protolith). There is no evidence of relict omphacite, so the rock has probably not reached (and retrogressed from) eclogite facies.
major mineralogy: For many years (at least since the 1990s when I was a grad student teaching assistant), this relatively coarse-grained attractive blueschist has appeared as a sample in our petrology lab course and end-of-the-semester lab exams. The sample is predominantly glaucophane, showing a weak but abrupt zoning to magnesio-riebeckite at the tips of some of the blades. Coarse poikioblastic lawsonite is also abundant. Scattered porphyroblasts of only weakly-zoned almandine garnet occur throughout the sample, as do sizable patches of white mica (“phengite”; primarily Mg+Fe-bearing muscovite, but some crystal tips are sufficiently [Mg+Fe]+Si-rich to grade into aluminoceladonite). Scattered epidote, titanite, rutile and zircon are widespread across the sample; some of the garnet is incipiently altered to chlorite and a bit of limonitic staining.
accompanying videos: Short videos featuring the mineral associations and optical properties of the lawsonite in this thin section offer a more detailed look at this sample.

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sample: FKM-110
locality: unlabeled, but believed to be from the Crestmore quarries area, Crestmore, Riverside Co., CA, USA.
rock type: test.
major mineralogy: andradite, vesuvianite, wollastonite.

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

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sample: FKM-111 (billet from Univ. Arizona petrology collection; sample BL-1)
locality: unlabeled (if the sample was donated to the petrology collection by S. Baldwin, it would be from New Caledonia; alternatively, it may be from one of the coastal California blueschist exposures).
rock type: test.
major mineralogy: glaucophane.

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sample: FKM-112 (billet from Univ. Arizona petrology collection)
locality: unlabeled, but believed to be from the Franklin marble, in the general region of Sussex Co., NJ across to Orange Co., NY, USA.
rock type: clinohumite-forsterite-spinel-phlogopite marble. Upper amphibolite to granulite facies meta-dolomite.
major mineralogy: Coarsely crystalline marble with now calcite >> dolomite (dolomite presumably has been significantly consumed to grow spinel and Mg silicates… dolomite is especially abundant within and adjacent to the amphibole, and optically appears slightly “dustier” than the accompanying calcite). Phlogopite, forsterite and spinel are the dominant porphyroblasts. Hydroxyl-clinohumite with patchy zones of more F-dominant clinohumite epitaxially overgrows some of the forsterite (and occasionally phlogopite). Scattered pargasite and apatite are present. Rare small ilmenite, zircon (likely originally detrital) and pyrrhotite are also present. Samples FKM-8, FKM-36 and FKM-184 are additional marbles from the adjoining Sussex Co., NJ/Orange Co., NY area containing humite group minerals. The description under FKM-8 also outlines the rationale for assuming small amounts of boron may be present in the Franklin area humite group minerals (and possibly also in olivine), and provides additional details about features of the normalization scheme.

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

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sample: FKM-113 (billet from Univ. Arizona petrology collection; sample Hawaii-29)
locality: Training School flow, Kailua, Oʻahu, Hawaiʻi, USA. Although the sample featured here is not necessarily from the same outcrop, Winchell, 1947 describes a sample collected from a “prominent outcrop… in orchard east of Kamehameha highway, 0.3 mile southwest of Kailua junction. Long. 157°45’40” W., Lat. 21°22’55” N.”.
rock type: olivine nephelinite. Compare to sample FKM-114 (olivine melilite nephelinite), also from the Honolulu area.
major mineralogy: specimen acquired for forsterite and nepheline.

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

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sample: FKM-114 (billet from Univ. Arizona petrology collection; sample Hawaii-30)
locality: Mōʻiliʻili quarry, Honolulu, Oʻahu, Hawaiʻi, USA.
rock type: olivine melilite nephelinite. Compare to sample FKM-113 (olivine nephelinite), also from the Honolulu area.
major mineralogy: specimen acquired for forsterite and melilite.

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

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sample: FKM-115 (this sample is similar to and from the same vicinity as FKM-101)
locality: Windham Co., VT, USA.
rock type: dolomite-chlorite schist. The sample is greenschist facies, with a likely protolith of some type of carbonate-metasomatized mafic (although a bit low in Ca) to ultramafic rock (although a bit high in Al).
major mineralogy: The large pale brown (in hand sample) carbonate rhombs in this schist were reported as ankerite, but have been confirmed by EPMA to be ferroan dolomite. These occur in a fine-grained chlorite matrix along with abundant small porphyroblasts of a Ti-rich hematite. Note the polysynthetic twinning parallel to the short and long axes of the rhomb in the dolomite (best seen in the crossed polar image), which differentiates it and other dolomite-group carbonates from the calcite-group carbonates (twin lamellae in calcite only cross the rhomb parallel to the long axis). Also compare the dolomite in this sample to the typically untwinned magnesite in FKM-133 from an ostensibly identical rock from the Alps.

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

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sample: FKM-116 (billet from Univ. Arizona petrology collection; sample 5-4-61-7; this sample is identical to the Wards collection garnet-sillimanite gneiss from the same locality)
locality: Hague township, Warren Co., NY, USA.
rock type: Garnet-sillimanite-[K-spar] gneiss. Middle-upper amphibolite facies metapelitic gneiss (with no co-existing cordierite present, this rock probably should not be considered granulite facies).
major mineralogy: test.

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

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sample: FKM-118 (billet courtesy of G. Haxel, U.S.G.S.-Flagstaff)
locality: Mountain Pass mine, San Bernardino Co., CA, USA.
rock type: carbonatite (sovite).
major mineralogy: calcite, barite, quartz, various tiny REE minerals.

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sample: FKM-119 (billet from Univ. Arizona petrology collection, courtesy of L. Anovitz)
locality: Brumado, Bahia, Brazil.
rock type: uvite-talc schist. Metamorphosed Mg-metasomatite(?)
major mineralogy: Gemmy greenish to reddish porphyroblasts of uvite in a snow-white fine-grained talc matrix. For the tourmaline, because the total Fe+Mn content is so low, all values of M3+/∑M (M = Fe+Mn) between 0.000 and 1.000 normalize to uvite. Uvite from this sample has been previously analyzed by SIMS (at Arizona State University) for B isotopes: δ11B = +13.4±1.1 ‰. Sample FKM-210 is another uvite-bearing sample from Brumado, but in magnesite rather than talc.
accompanying videos: Short videos featuring the mineral associations and optical properties of the uvite in this thin section offer a more detailed look at this sample.

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sample: FKM-120 (billet courtesy of J. Worthington, Univ. Arizona; sample 12TS97)
locality: Yasmin Valley, Tien Shan Mtns., Tajikistan.
rock type: nepheline cancrinite syenite.
major mineralogy: test.

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

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sample: FKM-121
locality: American #1 talc mine, Balmat, St. Lawrence Co., NY, USA.
rock type: tremolite schist. Amphibolite to granulite facies calcareous meta-evaporite, probably with some superimposed metasomatism.
major mineralogy: Almost entirely composed of bright green tremolite (up to 530 ppm Cr; up to 3460 ppm Mn; up to 1640 ppm Fe; compare to the pink tremolite in sample FKM-123), along with minor talc, an interlayer-deficient phlogopite (up to 2510 ppm Cr), calcite, apatite, quartz, zircon, sphalerite and galena. This sample is from the same general vicinity as samples FKM-122 and FKM-123.

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sample: FKM-122
locality: ZCA No. 4 mine, Balmat, St. Lawrence Co., NY, USA.
rock type: test.
major mineralogy: Abundant donpeacorite and clino-suenoite (most recently “manganocummingtonite” and previously “tirodite”; Oberti et al., 2018 [← subscription required]), with scattered As-rich chlorapatite (molar P:As almost 1:1, so near the chlorapatite-turneaureite boundary) and minor Mn-bearing uvite. For the “lower z” tourmaline, mathematically permissible values of M3+/∑M span from 0.467 to 1.000 and normalize to uvite throughout that range. For the “higher z” tourmaline, mathematically permissible values of M3+/∑M span from 0.445 to 0.890 (compositions which normalize to uvite), and from 0.890 to 1.000 (compositions which normalize to a hypothetical “oxy-uvite”). For both tourmaline normalizations presented in the composition table below, the aforementioned lowermost M3+/∑M values of 0.467 and 0.445 were utilized, although these are estimations and have not been independently measured.
accompanying videos: Short videos featuring the mineral associations and optical properties of the donpeacorite and clino-suenoite in this thin section offer a more detailed look at this sample.

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sample: FKM-123
locality: Gouverneur mine, Fowler, St. Lawrence Co., NY, USA.
rock type: tremolite schist. Amphibolite to granulite facies calcareous meta-evaporite, probably with some superimposed metasomatism..
major mineralogy: Almost entirely composed of pink tremolite (“hexagonite”; only up to 35 ppm Cr; up to 4970 ppm Mn; up to 1660 ppm Fe; compare to the bright green tremolite in sample FKM-121), along with minor talc, calcite, braunite and apatite. This sample is from the same general vicinity as samples FKM-121 and FKM-122.
accompanying videos: Short videos featuring the mineral associations and optical properties of the tremolite in this thin section offer a more detailed look at this sample.

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sample: FKM-124a (billet courtesy of B. Schumer, Univ. Arizona; sampled from the same slab as FKM-124b)
locality: Hpakant-Tawmaw jade tract, Kachin state, Burma.
rock type: blueschist to eclogite facies jadeitite.
major mineralogy: Essentially mono-mineralic jadeite.

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sample: FKM-124b (billet courtesy of B. Schumer, Univ. Arizona; sampled from the same slab as FKM-124a)
locality: Hpakant-Tawmaw jade tract, Kachin state, Burma
rock type: blueschist to eclogite facies jadeitite.
major mineralogy: Almost mono-mineralic jadeite showing weak patchy zoning in [NaAl] and [CaMg] components. Subordinate eckermannite is present with diffuse patches of richterite and rare sharp bands of potassic-richterite. Numerous thin veinlets traverse the sample, hosting a variety of poorly-identified alteration sheet silicates (interlayer-deficient mica and possibly vermiculite(?) and Mg-rich mixed-layer(?) clay); these veinlets also contain minor scattered harmotome.

There is currently no sample FKM-125.

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