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.