| Brassite | |
| Category: | Arsenate mineral |
| Formula: | Mg(AsO3OH)·4(H2O) |
| Imasymbol: | Bsi[1] |
| Strunz: | 8.CE.15 |
| Dana: | 39.01.07.01 |
| System: | Orthorhombic |
| Class: | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
| Symmetry: | Pbca |
| Unit Cell: | a = 7.472 Å, b = 10.891 Å, c = 16.585 Å; Z = 8 |
| Color: | White |
| Habit: | Cryptocrystalline crusts |
| Cleavage: | Perfect |
| Fracture: | Irregular/uneven, splintery |
| Tenacity: | Brittle |
| Luster: | Silky, dull, earthy |
| Streak: | White |
| Diaphaneity: | Translucent |
| Gravity: | 2.28 |
| Opticalprop: | Biaxial (+) |
| Refractive: | nα = 1.531 nβ = 1.546 nγ = 1.562 |
| Birefringence: | 0.031 |
| Pleochroism: | Non-pleochroic |
| 2V: | 80° |
| Dispersion: | r < v moderate |
| Solubility: | +++ HCl, + H2O |
| References: | [2] [3] [4] [5] |
Brassite is a rare arsenate mineral with the chemical formula Mg(AsO3OH)·4(H2O). It was named brassite, in 1973, to honor French chemist R`ejane Brasse, who first synthesized the compound. The type locality for brassite is Jáchymov of the Czech Republic.[3]
It occurs as an alteration of magnesium carbonate minerals by arsenic bearing solutions. It occurs associated with pharmacolite, picropharmacolite, weilite, haidingerite, rauenthalite, native arsenic, realgar and dolomite.[4]
Czech Republic:
France:
Germany: