samples FKM-51 to FKM-75

 

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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Lovozero Kola Russia lorenzenite in thin sectionLovozero Kola Russia lorenzenite in thin section

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

sample: FKM-51
locality: Lovozero massif, Kola Peninsula, Murmanskaja Oblast’, Russia.
rock type: agpaitic nepheline syenite.
major mineralogy: specimen acquired for lorenzenite.

 



Dara-i-Pioz Tajikistan reedmergnerite alkali granite in thin sectionDara-i-Pioz Tajikistan reedmergnerite alkali granite in thin section

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sample: FKM-52
locality: Darai-Pioz glacier, Alai range, Tien Shan Mtns., Tajikistan.
rock type: highly-evolved B-rich alkali granite.
major mineralogy: Almost entirely coarse reedmergnerite, intermixed with veinlet-like fine-grained quartz and very minor lepidolite. Sparse stillwellite-(Ce) adjacent to a chain of sparse purple manganoeudialyte(?), the latter with a tiny inclusion of sazykinaite-(Y) adjacent to a tiny inclusion of zeravshanite.
accompanying videos: Short videos featuring the mineral associations and optical properties of the reedmergnerite in this thin section offer a more detailed look at this sample.

 



Tres Pozos Mexico gillespite and cherchiaraite in thin sectionTres Pozos Mexico gillespite and cherchiaraite in thin section

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

sample: FKM-53 (billet courtesy of M. Origlieri, Univ. Arizona; separate specimen from sample FKM-53b)
locality: Madrelena mine, Tres Pozos, Baja California Norte, Mexico.
rock type: test.
major mineralogy: specimen acquired for gillespite. Also contains sanbornite, titantaramellite, quartz, bazirite, cherchiaraite-(Fe), alforsite, and at least one additional unidentified Ba-Ti-Si-Cl mineral.
accompanying videos: Short videos featuring the mineral associations and optical properties of the sanbornite in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-53
witherite (Ba0.93Sr0.06Na0.01)[CO3]
alforsite (high z;
most Ba+P+[OH]-enriched)
(Ba4.08Sr0.72Ca0.13Na0.03Mg0.01)[P0.863As0.143Al0.007O4]3(Cl0.46[OH]0.32F0.21)
alforsite (low z; most Cl-enriched) (Ba3.68Sr1.22Ca0.08Na0.02)[P0.843As0.15Al0.003O4]3(Cl0.67F0.20[OH]0.14)
alforsite (low z;
most Sr+As+F-enriched)
(Ba3.46Sr1.46Ca0.04Na0.03)[P0.823As0.173Al0.003O4]3(Cl0.61F0.31[OH]0.09)
bazirite Ba1.01(Zr0.84Sn0.19Ti0.02Hf~0.01)[Si2.91O9]
titantaramellite (most Si-rich?) (Ba3.96Na0.04Sr0.02)(Ti1.69Fe3+1.06Mg0.81Al0.08Cr0.07V0.05Mn3+0.04Sn0.01Sc0.010.18)
[B~1.67Si8.33O27]O2(Cl0.710.29)
titantaramellite (most B-rich?) (Ba3.94Na0.03Sr0.01)(Ti1.69Fe3+1.19Mg0.75Al0.09V0.07Mn3+0.05Cr0.03Sn0.010.12)
[B~1.81Si8.19O27]O2(Cl0.730.27)
cerchiaraite-(Fe) (Ba3.84Na0.04Sr0.01Ca0.010.10)(Fe3+1.87Al1.52Mg0.31Mn3+0.08Ti0.010.21)
[Si4.21O12]O2(OH)4[Si2.11O3(OH)4]([OH]1.00Cl0.84F0.16)
gillespite (Ba1.03Na0.01)(Fe2+0.93Ti0.02Al0.01)[Si3.99O10]
sanbornite (Ba2.00Na0.02Sr0.01)[Si3.96Al0.01O10]
celsian (Ba1.02K0.02Na0.01Mg0.01)[Si2.10Al1.87Fe3+0.03O8]
“unknown”
quartz not analyzed

 



Tres Pozos Mexico gillespite and cherchiaraite in thin sectionTres Pozos Mexico gillespite and cherchiaraite in thin section

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

sample: FKM-53b (separate specimen from sample FKM-53)
locality: Madrelena mine, Tres Pozos, Baja California Norte, Mexico.
rock type: test.
major mineralogy: specimen acquired for gillespite.
accompanying videos: Short videos featuring the mineral associations and optical properties of the titantaramellite, cerchiaraite and gillespite in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-53b
sphalerite not analyzed
witherite (Ba0.96Sr0.04Na0.01)[CO3]
bazirite (most Zr-rich) Ba1.04(Zr0.59Sn0.36Ti0.02Hf~0.01Fe3+0.01)[Si2.97O9]
bazirite (most Sn+Ti-rich) Ba1.06(Zr0.46Sn0.40Ti0.12Hf~0.01)[Si2.94O9]
titantaramellite (most Fe-rich) (Ba3.98Na0.02Sr0.01)(Ti1.74Mg0.90Fe3+0.49V0.43Cr0.21Mn3+0.11Al0.06Sc0.010.05)
[B~2.00Si8.00O27]O2(Cl0.840.16)
titantaramellite (most Mg+Cr-rich) (Ba3.99Na0.03Sr0.01)(Ti1.68Mg1.03V0.39Fe3+0.38Cr0.33Mn3+0.08Al0.06Sc0.020.03)
[B~1.91Si8.09O27]O2(Cl0.830.17)
cerchiaraite-(Fe)
tremolite (low z; most Mg-rich) (Sr0.06K0.05Na0.040.85)(Ca1.80Mn2+0.11Na0.09)(Mg4.24Fe2+0.68Mn2+0.06Zn0.01)
[Si7.88Fe3+0.10Al0.01O22]([OH]1.64F0.36)
tremolite (main z) (Sr0.08K0.06Na0.010.85)(Ca1.77Na0.14Mn2+0.10)(Mg4.11Fe2+0.79Mn2+0.09Zn0.01)
[Si7.90Fe3+0.09O22]([OH]1.60F0.40)
tremolite (high z;
most K+Sr-rich)
(K0.14Sr0.110.75)(Ca1.73Na0.20Mn2+0.05)(Mg3.38Fe2+1.34Mn2+0.27)
[Si7.89Fe3+0.10O22]([OH]1.73F0.27)
tremolite (high z;
most Fe+[OH]-rich)
(K0.06Sr0.060.88)(Ca1.89Na0.07Mn2+0.02)(Mg3.06Fe2+1.55Mn2+0.38Fe3+0.01)
[Si7.92Fe3+0.08O22]([OH]1.79F0.20)
gillespite (Ba1.01Na0.01Sr0.01)(Fe2+0.93Ti0.02Mn2+0.01Mg0.01Al0.01)[Si4.00O10]
sanbornite (Ba1.99Na0.01Sr0.01)[Si3.98Al0.01O10]
celsian (Ba0.99K0.03Na0.01Mg0.01)[Si2.18Al1.79Fe3+0.03O8]
“unknown”
quartz not analyzed

 



Franklin New Jersey rhodonite and jeffersonite in thin sectionFranklin New Jersey rhodonite and jeffersonite in thin section

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

sample: FKM-54
locality: Franklin mining district, Sussex Co., NJ, USA.
rock type: test.
major mineralogy: In hand sample the specimen is composed primarily of a somewhat friable mass of coarse pink rhodonite (“fowlerite”) cleavages. In thin section the rhodonite appears as both “clean” crystals and rattier masses (see unpolarized light thin section image), although there is no significant chemical difference between the two, and indeed the difference in appearance may simply be an orientation effect reflecting the quality of different cleavage directions. Characteristic of the “fowlerite” variety, this rhodonite contains ~6.3 wt% Zn (~0.6 apfu Zn). Interestingly, the description of Zn incorporation in rhodonite in DHZ’s “Single Chain Silicates” suggests that Zn appears to replace Fe2+, which is preferentially partitioned into the M4 metal site. With the recent discovery in 2016 of an M4Fe2+-dominant rhodonite-group end-member (ferrorhodonite) from Broken Hill, one might speculate whether a possible M4Zn-dominant rhodonite from Franklin would similarly qualify as a new rhodonite-group end-member. Crystal structure research by Nelson & Griffin, 2005 on changes to the size and geometry of the M4 and M5 metal sites in Zn-enriched rhodonite seems to indicate a new end-member would be warranted; hence, “fowlerite” (or “zincorhodonite”?) should probably be afforded species designation. Scattered franklinite is present; the larger masses seem to be a bit more Mg+Mn-rich, while smaller crystals, sometimes associated with sparse hematite, seem to be a bit more Zn-rich. Two yellow minerals are scattered in the sample. The more scarce pale-colored mineral, enclosed by coarser franklinite, is a Mn-rich andradite garnet with ~300 to ~700 ppm Na (after correction for the Zn Lα X-ray overlap) and close to 1000 ppm As (so together perhaps representing a tiny manganberzeliite component). The more abundant and widely-scattered strongly-colored mineral is a Zn+Mn-bearing diopside (“jeffersonite”). Its composition does not appear to vary significantly, although one grain partially enclosed in rare Zn+Mn-bearing actinolite is somewhat more Mg-enriched than the bulk. Sparse Zn-bearing phlogopite (~10 mol% end-member hendricksite component) and minor manganoan calcite are additionally present. A single tiny galena grain was identified.

mineral representative mineral compositions in FKM-54
galena Pb1.00S1.00
hematite (Fe3+1.98Mn3+0.01)O3
franklinite (most Zn-rich) (Zn0.88Mn2+0.10Fe2+0.02)(Fe3+1.85Al0.13Ti0.01Fe2+0.01)O4
franklinite (most Mn+Mg-rich) (Zn0.80Mn2+0.15Fe2+0.04Mg0.01)(Fe3+1.85Al0.13Ti0.01Fe2+0.01)O4
calcite (Ca0.97Mn2+0.03)[CO3]
andradite (Ca1.86Mn2+1.09Zn0.02Mg0.01Na0.01)(Fe3+1.38Al0.61Mn3+0.01)[Si0.987Al0.01As5+0.003O4]3
diopside (“jeffersonite”;
most Zn+Mn-rich)
(Ca0.76Na0.18Mn2+0.05)(Mg0.31Mn2+0.26Fe3+0.23Zn0.18Fe2+0.01)[Si1.94Al0.05Fe3+0.01O6]
diopside (“jeffersonite”;
most Mg-rich)
(Ca0.77Na0.17Mn2+0.06)(Mg0.47Fe3+0.19Mn2+0.17Zn0.13Fe2+0.04)[Si1.98Al0.01O6]
rhodonite (“fowlerite”; may
qualify as a new end-member)
Ca0.99Mn2+1.00Mn2+1.00Mn2+1.00(Zn0.61Mg0.21Mn2+0.07Mn3+0.06Fe3+0.05)[Si4.90Fe3+0.10O15]
actinolite (Na0.05K0.020.93)(Ca1.59Na0.29Mn2+0.12)(Mg3.37Fe2+0.46Mn2+0.45Zn0.44Fe3+0.27Ti0.01)
[Si7.94Al0.06O22]([OH]1.95F0.03O0.02)
phlogopite (K0.860.14)(Mg2.05Zn0.38FeT0.34MnT0.15Al0.050.03)[Si3.08Al0.92O10]([OH]1.87F0.13)

 



Oka Quebec pyrochlore bearing carbonatite in thin sectionOka Quebec pyrochlore bearing carbonatite in thin section

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

sample: FKM-55 (billet from Univ. Arizona economic geology collection; sample 96-15a).
locality: Oka complex, Oka, Laurentides, Québec, Canada.
rock type: carbonatite (sövite).
major mineralogy: specimen acquired for calcite, pyrochlore, phologopite, diopside, apatite. This sample is similar to FKM-41, also from Oka, but is poorer in silicates and pyrochlore.

 



Oka Quebec hauyne and melilite okaite in thin sectionOka Quebec hauyne and melilite okaite in thin section

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sample: FKM-56 (billet from Univ. Arizona economic geology collection; sample 96-13)
locality: Oka complex, Oka, Laurentides, Québec, Canada.
rock type: “okaite”. Intrusive equivalent of haüyne melilitite (i.e. haüyne melilitolite).
major mineralogy: specimen acquired for haüyne, melilite and britholite.
accompanying videos: Short videos featuring the mineral associations and optical properties of the melilite and phlogopite in this thin section offer a more detailed look at this sample.

 



Oka Quebec niocalite bearing carbonatite in thin sectionOka Quebec niocalite bearing carbonatite in thin section

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

sample: FKM-57 (billet from Univ. Arizona economic geology collection; sample 96-6)
locality: Oka complex, Oka, Laurentides, Québec, Canada.
rock type: carbonatite (sövite).
major mineralogy: specimen acquired for niocalite.
accompanying videos: Short videos featuring the mineral associations and optical properties of the niocalite in this thin section offer a more detailed look at this sample.

 



Meldon mine malayaite-bearing skarn in thin sectionMeldon mine malayaite-bearing skarn in thin section

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sample: FKM-58
locality: Meldon mine, Okehampton, Devon, England, UK.
rock type: test.
major mineralogy: specimen acquired for malayaite.

 



Waldheim Germany prismatine gneiss in thin sectionWaldheim Germany prismatine gneiss in thin section

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sample: FKM-59
locality: Waldheim, Döbeln, Saxony, Germany.
rock type: granulite.
major mineralogy: specimen acquired for prismatine and dravite. For comparison, other prismatine-bearing (and kornerupine-bearing) samples featured here include FKM-46 and FKM-67.
accompanying videos: Short videos featuring the mineral associations and optical properties of the prismatine in this thin section offer a more detailed look at this sample.

 



Umbozero mine Lovozero Kola Russia ussingite and serandite syenite in thin sectionUmbozero mine Lovozero Kola Russia ussingite and serandite syenite in thin section

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sample: FKM-60
locality: Umbozero mine, Alluaiv Mtn., Lovozero massif, Kola Peninsula, Murmanskaja Oblast’, Russia.
rock type: test.
major mineralogy: specimen acquired for ussingite and serandite.
accompanying videos: Short videos featuring the mineral associations and optical properties of the serandite and ussingite in this thin section offer a more detailed look at this sample.

 



Canta Peru dumortierite in thin sectionCanta Peru dumortierite in thin section

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

sample: FKM-61
locality: Canta province, Lima Department, Peru.
rock type: test. Compare this sample to the similar boron-bearing advanced argillic alteration assemblage in samples FKM-70 and FKM-187.
major mineralogy: specimen acquired for dumortierite.

 



Khibiny Kola Russia syenite in thin sectionKhibiny Kola Russia syenite in thin section

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sample: FKM-62
locality: Khibiny massif, Kola Peninsula, Murmanskaja Oblast’, Russia.
rock type: test.
major mineralogy: specimen acquired for eudialyte.

 



Tanzania spinel and pargasite marble in thin sectionTanzania spinel and pargasite marble in thin section

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

sample: FKM-63
locality: Mahenge, Morogoro region, Tanzania.
rock type: high grade spinel-bearing marble.
major mineralogy: specimen acquired for spinel (in the hand sample, but not in this thin section), along with pargasite, phlogopite and minor Cl-bearing fluorapatite, in a calcite + dolomite marble.

mineral representative mineral compositions in FKM-63
calcite not analyzed
dolomite not analyzed
fluorapatite (most Cl-rich) Ca4.99[P1.003O4]3(F0.61[OH]0.24Cl0.15)
pargasite (Na0.60K0.12Ca0.040.24)Ca2.00(Mg4.02Al0.77Ti0.14Fe3+0.04V0.02)[Si6.09Al1.91O22]([OH]1.27F0.42O0.29Cl0.02)
phlogopite (K0.90Na0.05Ba0.010.04)(Mg2.82Al0.14FeT0.01Ti0.010.02)[Si2.90Al1.10O10]([OH]1.58F0.39O0.02Cl0.01)
clinochlore (Mg4.58Al1.29FeT0.03Ti0.010.09)[Si2.88Al1.12O10]([OH]7.90F0.09O0.01)

 



Kipawa Canada miserite and agrellite in thin sectionKipawa Canada miserite and agrellite in thin section

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

sample: FKM-64
locality: Kipawa alkaline complex, Les Lacs-du-Témiscamingue, Abitibi-Témiscamingue, Québec, Canada.
rock type: metamorphosed alkali syenite.
major mineralogy: Miserite, agrellite (with rims of REE-bearing pectolite). Several additional samples from the Kipawa complex are featured as part of this collection and represent a variety of diverse mineral assemblages from the greater metamorphosed body; these include samples FKM-27, FKM-65, FKM-211 and FKM-315.

 



Kipawa Canada mosandrite and eudialyte in thin sectionKipawa Canada mosandrite and eudialyte in thin section

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

sample: FKM-65
locality: Kipawa alkaline complex, Les Lacs-du-Témiscamingue, Abitibi-Témiscamingue, Québec, Canada.
rock type: metamorphosed alkali syenite.
major mineralogy: Mosandrite, eudialyte, fluoro-richterite, microcline. Several additional samples from the Kipawa complex are featured as part of this collection and represent a variety of diverse mineral assemblages from the greater metamorphosed body; these include samples FKM-27, FKM-64, FKM-211 and FKM-315.
accompanying videos: Short videos featuring the mineral associations and optical properties of the mosandrite and fluoro-richterite in this thin section offer a more detailed look at this sample.

 



Cerro Sapo Bolivia sodalite ankerite burbankite carbonatite in thin sectionCerro Sapo Bolivia sodalite ankerite burbankite carbonatite in thin section

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sample: FKM-66
locality: Cerro Sapo, Ayopaya province, Cochabamba Department, Bolivia.
rock type: ankerite-sodalite carbonatite.
major mineralogy: Primarily massive sodalite with abundant coarse subhedral crystals of a dolomite-group carbonate. The cores of the carbonate are a vuggy (former solid or fluid inclusions?) Fe-rich dolomite grading outwards to a clean Mg-rich ankerite. The sodalite is locally altered to small patches of analcime. The 2nd order blue birefringence mica-like blade in the NE corner of the XP image was on first inspection thought to be phlogopite, but was subsequently found to be B(-) with a 2V° ≈ 80°; this material was verified by EPMA to be the Na-Al-carbonate dawsonite (for elements z ≥ 9, only Na and Al were present, but a good quantitative analysis was not possible due to the mineral’s extreme instability under the electron beam, even using a 10 μm defocused beam and slow raster). Note that dawsonite’s actual maximum birefringence is δ = 0.130 (so ~7th to ~8th order!), but this grain is fortuitously oriented to give an almost perfectly centered optic axis figure. The main dawsonite mass encloses small blades of orthoclase (these are also sparsely scattered elsewhere in the sample), as well as a zeolite that appears to be a Sr-dominant end-member of edingtonite (based on the Al:Si ratio and estimated H2O content). Small but abundant grains of REE-rich burbankite, Th-rich ancylite-(Ce) and Ca-rich strontianite are widely scattered within the sample, and in some cases are intergrown together. EPMA analyses of both REE-bearing carbonates gave high totals (~106 wt%) but acceptable stoichiometries and charge balances. A single small mass of REE-bearing goyazite was also observed.
accompanying videos: Short videos featuring the mineral associations and optical properties of the dawsonite and ankerite in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-66
dolomite-dominant dolomite group ss
(vuggy interior)
(Ca0.97Mn2+0.03)(Mg0.64Fe2+0.34Mn2+0.02)[CO3]2
ankerite-dominant dolomite group ss
(clean exterior)
(Ca0.98Na0.01Mn2+0.01)(Fe2+0.60Mg0.37Mn2+0.04)[CO3]2
strontianite (Sr0.77Ca0.17Ba0.02Ce0.01La0.01Na0.01)[(CO3)0.99(CO3F)0.01]
dawsonite not analyzed, due to extreme damage under the electron beam
burbankite (Na2.27Ca0.66Sr0.07)(Sr2.20Ce0.26La0.15Ba0.12Nd0.10Th0.08Pr0.03Sm0.03Gd0.03)
[(CO3)4.96(CO3F)0.04]
ancylite-(Ce) (Ce0.37La0.19Th0.18Nd0.13Pr0.04Sm0.03Gd0.02Ba0.01Sr0.03)(Sr0.84Ca0.17)
[CO3]2([OH]0.90F0.10) . ~1H2O
goyazite (Sr0.58Ba0.28Ca0.10Ce0.02La0.01Nd0.01Na0.01)(Al2.99Fe3+0.01)
{[P0.99Si0.01O4][P1.00O3.02(OH)0.98]}([OH]5.91F0.09)
orthoclase (K0.98Na0.02)[Si2.98Al1.02O8]
sodalite Na5.92[Si5.92Al6.08O24] . Na2.01(Cl1.97[CO3]0.02)
“Sr-edingtonite?” (Sr0.38Ca0.29Ba0.22K0.07Na0.07)[Si2.96Al2.04O10] . ~4H2O
analcime Na0.94[Si1.97Al1.03O6] . H2O

 



Australia kornerupine gneiss in thin sectionAustralia kornerupine gneiss in thin section

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

sample: FKM-67
locality: Plenty River mine area, Harts Range, NT, Australia. This material is ostensibly identical to that found at the classic Mt. Riddock station locality, but it’s unclear if the Plenty River mine area is a distinct occurrence in the Harts Range, or simply an imprecise reference to the Mt. Riddock locality.
rock type: test.
major mineralogy: test. For comparison, other prismatine-bearing (and kornerupine-bearing) samples featured here include FKM-46 and FKM-59.

 



Longido Tanzania corundum ruby zoisite and tschermakite in thin sectionLongido Tanzania corundum ruby zoisite and tschermakite in thin section

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sample: FKM-68
locality: Longido area, Mt. Kilimanjaro region, Tanzania. Note: the locality for this sample is distinguished here from the nearby and similar Mundarara mine locality because the dealer label only specified “Longido”; however, as the specimen was purchased from a lapidary supplier and not a mineral dealer perhaps more accustomed to collectors’ desire of precise locality data, it is in fact possible this sample actually does come from the more well-known Mundarara locality.
rock type: corundum-zoisite-pargasite gneiss. Presumably a higher pressure (eclogite facies) equivalent of corundum-bearing amphibolite (i.e., akin to sample FKM-24); estimated at between 700°-850° C and between ~10-20 kbars, according to experimental phase relations. Note that unlike FKM-24, the amphibole in this sample is actually pargasite rather than tschermakite. Both this sample and FKM-24 (as well as FKM-290; see discussion below) are thus granulite to eclogite facies metamorphic equivalents of what were probably originally gabbro to gabbroic anorthosite.
major mineralogy: Porphyroblasts of pale red Cr-bearing corundum (“ruby”) in a matrix of coarse zoisite and pargasite. Inclusions of remnant(?) Cr- and Fe3+-enriched spinel and pumpellyite-(Al) occur, primarily within the zoisite. Minor retrograde alteration (corundum veined by diaspore and chlorite along zoisite-amphibole boundaries) is also present. This specimen is similar to but not identical to sample FKM-290 (see link above) from Mundarara, ~27 km W of Longido.
accompanying videos: Short videos featuring the mineral associations and optical properties of the zoisite and pargasite in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-68
spinel (Mg0.62Fe2+0.35Mn2+0.01Zn0.01)(Al1.76Cr0.23Fe3+0.01)O4
corundum (Al1.99Cr0.01)O3
diaspore (Al0.99Cr0.01)O(OH)
zoisite Ca1.00(Ca0.98Sr0.02)Al1.01Al1.00(Al0.94Fe3+0.05Cr0.01)O1.00[Si1.97Al0.03O7][Si0.98Al0.02O4](OH)
pumpellyite-(Al) (Ca1.96Na0.02Fe2+0.01Mn2+0.01)(Al0.63Mg0.32FeT0.05)Al2.00
[Si1.98Al0.02O7][Si0.99Al0.01O4]([OH]~1.36O~0.64) . H2O
pargasite (most Cr-rich) (Na0.52K0.110.37)(Ca1.97Na0.03)(Mg3.23Al1.07Fe3+0.29Fe2+0.26Cr0.11Ti0.02Mn2+0.01Ni0.01)
[Si5.91Al2.08O22]([OH]1.96O0.04)
clinochlore (Ca0.01K0.01)(Mg3.96Al1.23FeT0.54Cr0.09MnT0.01Ni0.010.16)[Si2.81Al1.19O10](OH)8.00

 



Mautia Hill Tanzania yoderite whiteschist in thin sectionMautia Hill Tanzania yoderite whiteschist in thin section

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

sample: FKM-69 (separate specimen from sample FKM-69b)
locality: Mautia Hill, Kongwa, Kongwa district, Dodoma region, Tanzania.
rock type: yoderite-kyanite-talc metaquartzite (“whiteschist”). UHP eclogite facies sepiolitic(?) metapelite with accompanying metasomatism?
major mineralogy: Yoderite overgrowing orange kyanite, in a matrix of talc and dominant quartz. Scattered hematite, with some associated rutile (the 0.04 apfu Mn corresponds to ~25800 ppm Mn; also with ~102 ppm Cr), is also present.

mineral representative mineral compositions in FKM-69
rutile (Ti0.94Mn4+?0.04Fe3+0.01)O2
hematite (Fe3+1.90Mn3+0.06Al0.01Ti0.01Mg0.01)O3
kyanite (Al1.97Fe3+0.03)O1.00[Si0.98Al0.02O4]
yoderite (Mg1.90Fe2+0.05Mn2+0.05)(Al5.57Fe3+0.40Mg0.03Ti0.01)O2[Si0.993P0.075O4]4([OH]1.99O0.01)
talc Ca0.01(Mg2.75Al0.17FeT0.020.06)[Si3.91Al0.09O10]([OH]1.98F0.02)
quartz not analyzed

 



Mautia Hill Tanzania yoderite whiteschist in thin sectionMautia Hill Tanzania yoderite whiteschist in thin section

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

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

sample: FKM-69b (separate specimen from sample FKM-69. Two thin sections cut from the same billet are shown here; the upper and lower image pairs represent samples FKM-69b-1 [broken during use as an in-class teaching sample] and FKM-69b-2, respectively).
locality: Mautia Hill, Kongwa, Kongwa district, Dodoma region, Tanzania.
rock type: yoderite-kyanite-talc metaquartzite (“whiteschist”). UHP eclogite facies sepiolitic(?) metapelite with accompanying metasomatism?
major mineralogy: Yoderite overgrowing orange kyanite, in a matrix of talc and dominant quartz.
accompanying videos: Short videos featuring the mineral associations and optical properties of the yoderite in this thin section offer a more detailed look at this sample.

 



Japan dumortierite and foitite advanced argillic alteration assemblage in thin sectionJapan dumortierite and foitite advanced argillic alteration assemblage in thin section

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

sample: FKM-70
locality: Tsukigata mine, Koriyama, Fukushima Prefecture, Honshu Island, Japan.
rock type: test. Compare this sample to the similar boron-bearing advanced argillic alteration assemblage in sample FKM-61 and FKM-187.
major mineralogy: Dumortierite, foitite.
accompanying videos: Short videos featuring the mineral associations and optical properties of the foitite in this thin section offer a more detailed look at this sample.

 



Alto Chapare Bolivia povondraite in thin sectionAlto Chapare Bolivia povondraite in thin section

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

sample: FKM-71
locality: Cristalmayu valley area, Alto Chapare district, Chapare province, Cochabamba Department, Bolivia.
rock type: test.
major mineralogy: Abundant large zoned tourmaline ranging from dominant povondraite to alumino-povondraite, with small patches of a new tourmaline (“K-povondraite”). Additional crystals of a notably lower-Fe oxy-dravite are scattered in the matrix of hydromagnesite, K-feldspar, hematite and minor talc. Reported M3+/∑M (where M = Fe+Mn) and O/(O+OH) in the tourmaline analyses are estimations and have not been independently measured. For the povondraite-related tourmalines, values of M3+/∑M between 0.708 and 0.825 normalize to un-named tourmaline end-members inconsistent with their very high Fe contents (i.e. oxygen apfu in the “W” site becomes less than 0.50); for values of M3+/∑M < 0.708, the normalizations fail altogether (oxygen apfu in the “W” site calculates to less than zero). For the oxy-dravite only, values of M3+/∑M < 0.12 normalize to dravite instead of oxy-dravite; although mathematically permissible, this would again seem to be inconsistent with the overall highly-oxidized assemblage present in the sample.
accompanying videos: Short videos featuring the mineral associations and optical properties of the povondraite in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-71
oxy-dravite (in matrix) (Na0.91K0.060.06)(Al1.93Mg0.55Fe2+0.49Ti0.03)(Al4.45Mg1.00Fe3+0.55)
[Si5.97Al0.02P0.01O18](BO3)3(OH)3(O0.92F0.08)
alumino-povondraite-dominant tourmaline ss (Na0.80K0.20)Fe3+3.00(Al2.24Mg2.13Fe3+1.01Ti0.28Fe2+0.24V0.01)
[Si6.09O18](BO3)3(OH)3O1.00
povondraite-dominant tourmaline ss (Na0.64K0.37Ca0.06)Fe3+3.00(Fe3+3.05Mg1.69Fe2+0.58Al0.55Ti0.03V0.01)
[Si6.10O18](BO3)3(OH)3O1.00
“K-povondraite”-dominant tourmaline ss (K0.58Na0.45)Fe3+3.00(Fe3+3.82Mg1.82Fe2+0.30Al0.01Ti0.01V0.01)
[Si5.96P0.06O18](BO3)3(OH)3O1.00

 



Klause Austria kolbeckite-bearing latite in thin sectionKlause Austria kolbeckite-bearing latite in thin section

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

sample: FKM-72
locality: Schlarbaum quarry, Klause, Bad Gleichenberg, Styria, Austria.
rock type: altered latite.
major mineralogy: Kolbeckite present in the hand sample, but not observed in this thin section; plagioclase phenocrysts in a volcanic matrix.

 



Langesundfjord Norway hiortdahlite syenite in thin sectionLangesundfjord Norway hiortdahlite syenite in thin section

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sample: FKM-73
locality: Stokkøya, Langesundfjorden, Larvik, Vestfold, Norway.
rock type: nepheline syenite.
major mineralogy: specimen acquired for hiortdahlite.

 



Palabora South Africa carbonatite in thin sectionPalabora South Africa carbonatite in thin section

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

sample: FKM-74 (billet from Univ. Arizona economic geology collection; sample PAL-3)
locality: Palabora mine, Loolekop, Phalaborwa, Limpopo province, South Africa.
rock type: “syenite” (may be a “K-fenite” rather than a true igneous syenite) associated with a carbonatite.
major mineralogy: microcline, amphibole (occurs as large minimally-zoned crystals with a composition roughly halfway along the ferri-winchite/potassic-richterite join… this is the earliest amphibole and may represent an igneous amphibole associated with the carbonatite complex emplacement; later thin rims and interior patches on the NaCa-amphibole, as well as being the dominant composition of more finely-crystalline adjacent amphibole aggregates, is a Fe-rich actinolite that appears to be secondary; a seemingly still later “boundary” layer between the main coarse NaCa-amphibole and actinolite aggregates is even more Fe-rich ferro-actinolite; similar but slightly less Fe-rich material also forms scattered rims outside of the actinolite rims and actinolite aggregates), apatite (notably as large crystals in a calcite vein surface, in the hand sample).
accompanying videos: Short videos featuring the mineral associations and optical properties of the zoned winchite and microcline in this thin section offer a more detailed look at this sample.

mineral representative mineral compositions in FKM-74
digenite (Cu8.93Fe0.06)S5.00
bornite (poor stoichiometry;
re-analysis warranted)
Cu5.15Fe1.07S4.00
calcite (main) Ca1.00[CO3]
calcite (patchy highest z) (Ca0.96Sr0.02Fe2+0.01Mg0.01)[CO3]
“hydroxylsynchysite-(Ce)”
(admixed with Ca-REE-Fe-silicate;
see below)
(Ca0.86Mg~0.07K~0.05Sr0.01)(Ce0.51La0.31Nd0.13Pr0.05)[CO3]2([OH]0.65F0.35)
barite (Ba0.97Sr0.02Na0.01)[S1.00O4]
fluorapatite (core; most F-rich) (Ca4.84Sr0.06Ce0.02Na0.02La0.01Nd0.01)[P0.993Si0.007O4]3(F0.98[OH]0.01)
fluorapatite (rim; most REE+Si-rich) (Ca4.82Sr0.06Ce0.04Na0.03La0.02Nd0.02Y0.01)[P0.977Si0.023O4]3(F0.85[OH]0.14Cl0.01)
monazite-(Ce) (inclusion in apatite) (Ce0.50La0.31Nd0.10Pr0.04Th0.01Ca0.01)[P1.00Si0.02O4]
titanite (Ca0.96Ce0.01Nd0.01)(Ti0.93Fe3+0.05V0.01Zr0.01)(O0.94F0.03[OH]0.03)[Si0.97Al0.01Fe3+0.01O4]
~midway along the join between
(Ca[REE]2)(Fe3+2Fe2+2)[Si2O7][SiO4]3
and (Ca2[REE])(Fe3+3Fe2+)[Si2O7][SiO4]3
(admixed with “hydroxylsynchysite-(Ce)”)
(Ca1.44Ce0.79La0.41Nd0.17Pr0.07Sr0.06Mn2+0.02Sm0.01)(Fe3+1.73Fe2+1.42Al0.75Mg0.07Ti0.03)
[Si1.98Al0.02O7][Si1.00O4]3
epidote/allanite with compositional variability; analyses pending
[ferri-winchite]-[potassic-richterite] join-dominant B([NaCa]/[CaCa])-amph ss
(main; most Mg-rich)
(K0.42Na0.06Sr0.010.51)(Ca1.32Na0.67)(Mg3.79Fe2+0.92Fe3+0.26Mn2+0.01Ti0.01)
[Si7.92Al0.08O22]([OH]1.36F0.61O0.03)
actinolite-dominant B([NaCa]/[CaCa])-amph ss
(interior patches & inner rims)
(Na0.03K0.020.95)(Ca1.97Na0.03)(Mg2.80Fe2+2.12Mn2+0.05Fe3+0.03)
[Si7.96Al0.03Fe3+0.01O22]([OH]1.92F0.08)
ferro-actinolite-dominant
B([NaCa]/[CaCa])-amph ss
(“boundary” layer & outer rims; most Fe-rich)
(K0.010.99)(Ca1.97Mn2+0.02Na0.01)(Fe2+2.94Mg1.97Mn2+0.08Fe3+0.01)
[Si7.98Fe3+0.01O22](OH)2.00
phlogopite (K0.96Na0.010.03)(Mg2.14FeT0.77Ti0.06MnT0.010.02)
[Si3.02Al0.95Fe3+0.03O10]([OH]1.39F0.48O0.12Cl0.01)
microcline (main) (K0.97Na0.03)[Si2.98Al0.98Fe3+0.04O8]
microcline
(patchy & vuggy; most Na-rich)
(K0.88Na0.13)[Si2.97Al1.03O8]
microcline
(patchy; most Ba-rich)
(K0.91Ba0.05Na0.04)[Si2.92Al1.07Fe3+0.01O8]
microcline
(patchy; most K-rich)
(K0.99Na0.01)[Si2.98Al1.01O8]

 



Chongwe River Zambia staurolite lusakite and cobalt-bearing hogbomite in thin sectionChongwe River Zambia staurolite lusakite and cobalt-bearing hogbomite in thin section

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

sample: FKM-75 (billet courtesy of S. Vrána, Czech Geologic Survey; this sample is a part of the material collected by M.W.C. Barr in 1970 and presented to the Geological Survey of Zambia)
locality: confluence of the Mwambashi and Musangashi rivers, Chongwe River region (~120 km E. of Lusaka), Zambia.
rock type: staurolite-kyanite-magnetite gneiss. Amphibolite facies “ferrolite” (due to this rock’s unusual bulk composition, its protolith has not been definitively ascertained).
major mineralogy: Abundant blue(!) Co-bearing staurolite (“lusakite”), associated with and sometimes overgrowing abundant kyanite, with minor sillimanite, all hosted by intergrown magnetite, hematite, ilmenite, and quartz. Tiny violet “cobaltohögbomite-2N2S“, a potentially new member of the högbomite family, is abundantly scattered within the oxide. Minor phyllosilicate alteration consists of both margarite and a more abundant cobaltoan clinochlore. The sample is poor in sulfides, with only a few scattered grains of cobalt-pentlandite and linnaeite. Note that the site fillings in the staurolite and “cobaltohögbomite-2N2S” are estimated and have not be verified by crystal structure analyses. Similarly, M3+/∑M ratio and OH content of the staurolite are also estimated, while the polysome of the högbomite species is based off of the reported polysome for cobaltoan ferrohögbomite-2N2S from the same locality (see the mindat.org ferrohögbomite-2N2S entry). Scattered rutile (also with ~196 ppm Co and ~150 ppm Mn) is also present.

mineral representative mineral compositions in FKM-75
cobalt-pentlandite (Co7.93Ni0.97Fe0.10)S8.00
linnaeite (Co2+0.68Ni2+0.32)(Co3+1.97Fe3+0.03)S4.00
rutile (Ti0.99Fe3+0.01)O2
hematite (Fe3+0.81Fe2+0.14Co0.05)(Fe3+0.79Ti0.19V0.02)O3
ilmenite (Fe2+0.82Co0.06Fe3+0.05Mg0.04Mn2+0.02)(Ti0.95Fe3+0.05)O3
magnetite (Fe2+0.93Co0.06Ni0.01)(Fe3+1.99Al0.01)O4
“cobaltohögbomite-2N2S (Al0.55Fe2+0.44)(Al3.54Ti0.45Ga0.01)O7([OH]0.94F0.06) .
(Co0.88Mg0.72Fe2+0.29Ni0.07Zn0.03Mn2+0.01)(Al3.23Fe3+0.77)O8
sillimanite (Al1.97Fe3+0.02)O1.00[Si0.97Al0.03O4]
kyanite (Al1.99Fe3+0.01)O1.00[Si0.99Al0.01O4]
staurolite 4Al2.00O1.00[Si0.97Al0.03O4] .
(Al0.84Mg0.10Ti0.05Mn2+0.01)(Fe2+1.08Mg0.51Co0.38Ni0.02Zn0.01)(O2.80[OH]1.16F0.04)
margarite (Ca0.70Na0.280.02)(Al1.97FeT0.06Mg0.05Co0.010.91)[Si2.12Al1.88O10](OH)2.00
clinochlore (Mg3.51Al1.37FeT0.80Co0.19Ni0.050.08)[Si2.62Al1.38O10]([OH]7.98F0.02)
quartz not analyzed

accompanying videos: Short videos featuring the mineral associations and optical properties of the “cobaltohögbomite-2N2S, kyanite and blue Co-bearing staurolite 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)
“cobaltohögbomite”
PPL: violet/brown-violet pleochroism, high relief;
XP: birefringence color masked by body color of mineral;
with quartz and magnetite
presumably U(-)
but no optic figure available
kyanite
PPL: colorless, high relief;
XP: up to 1st order orange δ;
with quartz, staurolite and magnetite
staurolite
PPL: weak medium/dark blue pleochroism, high relief;
XP: birefringence color masked by body color of mineral;
with quartz, kyanite and magnetite

 



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