Pharmacosiderite
| Pharmacosiderite | |
|---|---|
 |
|
| General | |
| Category | Arsenate minerals |
|
Formula (repeating unit) |
KFe4(AsO4)3(OH)4·(6-7)H2O |
| Strunz classification | 8.DK.10 |
| Crystal system | Isometric |
| Crystal class | Hextetrahedral (43m) H-M symbol: (4 3m) |
| Space group | P43m |
| Identification | |
| Formula mass | 873.38 g/mol |
| Color | Greens, browns, yellows |
| Crystal habit | Massive to Crystalline |
| Cleavage | Distinct on the [100] |
| Fracture | Brittle |
| Mohs scale hardness | 2 1/2 |
| Luster | Adamantine |
| Streak | yellowish green |
| Diaphaneity | Subtransparent to subtranslucent |
| Density | 2.9 g/cm³ |
| Ultraviolet fluorescence | None |
| References | |
Pharmacosiderite is a hydrated basic ferric arsenate, with chemical formula KFe4(AsO4)3(OH)4·(6-7)H2O and a molecular weight of 873.38 g/mol. It consists of the elements arsenic, iron, hydrogen, potassium, sodium and oxygen. It has a Mohs hardness of 2 to 3, about that of a finger nail. Its specific gravity is about 2.7 to 2.9, has indistinct cleavage, and is usually transparent or translucent. It has a yellow or white streak and a yellow, green, brown or red color. Its lustre is adamantine, vitreous and resinous, and it has conchoidal, brittle and sectile fracture.
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