Getchellite
| Getchellite | |
|---|---|
Getchellite from Khaidarkan, Fergana Valley, Osh Oblast, Kyrgyzstan. Specimen size 3.6 cm. | |
| General | |
| Category | Sulfide mineral |
| Formula | AsSbS3 |
| IMA symbol | Get |
| 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 | |
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.