Getchellite
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Getchellite is a rare sulfide of arsenic and antimony, AsSbS3, that was discovered by B. G. Weissberg of the New Zealand Department of Scientific and Industrial Research in 1963, and approved as a new species by the International Mineralogical Association in 1965. Many metal sulfides are grey to black, but a few are brightly colored. Orpiment is yellow to brownish gold, cinnabar is deep red and getchellite is a bright orange red.
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Getchellite | |
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General | |
Category | Sulfide mineral |
Formula (repeating unit) | AsSbS3 |
IMA symbol | Get[1] |
Strunz classification | 2.FA.35 |
Dana classification | 2.11.1.2 |
Crystal system | Monoclinic |
Crystal class | Prismatic (2/m) (same H-M symbol) |
Space group | P21/a |
Identification | |
Formula mass | 293.81 g/mol |
Color | Dark red, sometimes with a purple to green iridescent tarnish |
Crystal habit | Subhedral crystals and massive with a platy texture |
Twinning | Simple and polysynthetic twins with the twin plane and composition plane parallel to {001} |
Cleavage | Perfect on {001} |
Fracture | Splintery |
Tenacity | Sectile; cleavage flakes are flexible and inelastic |
Mohs scale hardness | 1.5 to 2 |
Luster | Vitreous to pearly on cleavage surfaces, otherwise resinous |
Streak | Orange red |
Diaphaneity | Transparent |
Specific gravity | 3.92 (observed) 4.0 (calculated) |
Optical properties | Biaxial (+), 2V=46° |
Refractive index | n = 2.720. Dispersion r > v strong |
Melting point | 340 °C to 355 °C |
Other characteristics | Not radioactive |
References | [2][3][4] |
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