Sarkinite
Sarkinite, synonymous with chondrarsenite and polyarsenite, is a mineral with formula Mn2(AsO4)(OH). The mineral is named for the Greek word σάρκιυος, meaning made of flesh, for its red color and greasy luster. The mineral was first noted in Sweden in 1865 as chondrarsenite, though not identified as sarkinite until 1885.
| Sarkinite | |
|---|---|
| General | |
| Category | Arsenate minerals |
| Formula (repeating unit) | Mn2(AsO4)(OH) |
| IMA symbol | Srk |
| Strunz classification | 8.BB.15 |
| Dana classification | 41.6.3.3 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | P2m |
| Unit cell | a = 12.7795(13) Å b = 13.6127(14) Å c = 10.2188(11) Å β = 108.834(2)°; Z = 16 |
| Identification | |
| Color | Red to yellow |
| Crystal habit | Tabular or granular |
| Cleavage | Distinct on {100} |
| Fracture | Irregular/Uneven, Conchoidal |
| Mohs scale hardness | 4–5 |
| Luster | Greasy |
| Streak | Red to yellow |
| Diaphaneity | Semitransparent |
| Density | 4.08 to 4.18 g/cm3 (measured) |
| Optical properties | Biaxial (−) |
| Refractive index | nα=1.793, nβ=1.807, nγ=1.809 |
| Birefringence | δ = 0.016 |
| Pleochroism | Weak |
| 2V angle | 83° (measured) |
| Dispersion | r > v or r < v |
| Absorption spectra | X > Z > Y |
| Solubility | Readily soluble in dilute acids |
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