Vyalsovite, a new sulfide-hydroxide of iron, calcium, and aluminum

The new mineral vyalsovite, FeS.Ca(OH)2.Al(OH)3, has been found in forsterite skarns at the lower contact of the Talnakh gabbro-dolerite intrusion in Devonian dolomite. It occurs as 5 to 150 mu m grains and veinlets in association with valleriite, diaspore, djerfisherite, serpentine and magnetite. T...

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Bibliographic Details
Published in:The American mineralogist 1992-01, Vol.77 (1-2), p.201-206
Main Authors: Evstigneeva, Tatiana L, Genkin, Alexandr D, Sandomirskaya, Sofya M, Trubkin, Nikolay V
Format: Article
Language:English
Subjects:
Aluminum
Asia
cell dimensions
chemical composition
Commonwealth of Independent States
crystal structure
Devonian
diabase
Dolomite
electron probe data
formula
forsterite
gabbros
hydrothermal alteration
hydroxides
igneous and metamorphic rocks
igneous rocks
Krasnoyarsk Russian Federation
Krasnoyarsk Russian Republic
metamorphic rocks
metasomatic rocks
metasomatism
mineral assemblages
mineral composition
mineral data
mineralogy
Minerals
nesosilicates
new minerals
nonsilicates
Norilsk region
olivine group
optical properties
orthosilicates
oxides
Paleozoic
Petrology
plutonic rocks
processes
Russian Federation
Russian Republic
silicates
skarn
sulfides
Talnakh Intrusion
Taymyr Dolgan-Nenets Russian Federation
Taymyr Dolgan-Nenets Russian Republic
USSR
vyalsovite
X-ray diffraction data
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Description
Summary:The new mineral vyalsovite, FeS.Ca(OH)2.Al(OH)3, has been found in forsterite skarns at the lower contact of the Talnakh gabbro-dolerite intrusion in Devonian dolomite. It occurs as 5 to 150 mu m grains and veinlets in association with valleriite, diaspore, djerfisherite, serpentine and magnetite. This assemblage formed as a result of the replacement of minerals included in an earlier assemblage of chalcopyrite, forsterite, and spinel. Vyalsovite has an unusual composition and unique optical properties. In polished section, the mineral displays extreme reflection pleochroism from dark grey to crimson red. Reflectance in air at 540 nm is 8.15% for Ro and 11.4% for Re. Reflectance spectra of vyalsovite Ro and Re cross several times in the range from 250 to 800 nm. The optic sign of vyalsovite changes four times within this range. No other known ore mineral possesses such optical properties. According to X-ray and electron diffraction data, vyalsovite is orthorhombic (possible space groups Cmmm, C222, Cmm2, Cm2m, Cmma, C2ma) with a 14.20(1), b 20.98(2), c 5.496(4) Angstrom ; Dcalc. 1.96 g/cm3 for the ideal composition; Z = 8. The strongest XRD lines are 5.40(100), 2.16(50), 4.76(40), 1.973(30), 1.894(30, broad) 1.846(30) Angstrom.
ISSN:0003-004X
1945-3027