Stillwaterite
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| Stillwaterite | |
|---|---|
| General | |
| Category | Arsenide mineral |
| Formula | Pd8As3 |
| IMA symbol | Slw[1] |
| Strunz classification | 2.AC.10a |
| Crystal system | Trigonal |
| Crystal class | Pyramidal (3) or rhombohedral (3) H-M symbol: (3 or 3) |
| Space group | P3 or P3 |
| Unit cell | a = 7.399(4) c = 10.311(15) [Å] V = 491.58 Å3 |
| Identification | |
| Formula mass | 1076.12 g/mol |
| Color | light creamy gray |
| Crystal habit | microscopic crystals |
| Mohs scale hardness | 4.5 |
| Luster | metallic |
| Diaphaneity | opaque |
| Density | 10.96 g/cm3 |
| Optical properties | weakly anisotropic in air; distinctly anisotropic in oil; no bireflectance; uniaxial |
| Pleochroism | no |
| Other characteristics | non-radioactive |
| References | [2][3][4][5][6][7][8][9][10][11] |
Stillwaterite is a palladium arsenide mineral which has a general formula of Pd8As3. Stillwaterite was first discovered in the Banded and Upper zones of the Stillwater igneous complex in Montana, United States, and has been reported in the Lac-des-Iles area of Ontario, Canada. Outside of North America, this rare mineral has been found in northern Finland.
Stillwaterite has hexagonal symmetry, meaning that it has four crystallographic axes: three are horizontal axes of equal length, and the fourth is a vertical axis of different length.