Torbernite
Torbernite, also known as chalcolite, is a relatively common mineral with the chemical formula Cu[(UO2)(PO4)]2(H2O)12. It is a radioactive, hydrated green copper uranyl phosphate, found in granites and other uranium-bearing deposits as a secondary mineral. The chemical formula of torbernite is similar to that of autunite in which a Cu2+ cation replaces a Ca2+ cation. Torbernite tends to dehydrate to metatorbernite with the sum formula Cu[(UO2)(PO4)]2(H2O)8.
| Torbernite | |
|---|---|
Torbernite crystals from Mashamba West Mine, Kolwezi, Katanga Province, Democratic Republic of the Congo | |
| General | |
| Category | Phosphate minerals |
| Formula (repeating unit) | Cu[(UO2)(PO4)]2(H2O)12 |
| IMA symbol | Tor |
| Strunz classification | 8.EB.05 |
| Crystal system | Tetragonal |
| Crystal class | Ditetragonal dipyramidal (4/mmm) H-M symbol: (4/m 2/m 2/m) |
| Space group | I4/mmm |
| Identification | |
| Formula mass | 641 – 713 g/mol, depending the degree of water loss |
| Color | Emerald green to apple green |
| Crystal habit | Tabular crystals; Foliated to earthy masses and encrustations |
| Twinning | Rare on [110] |
| Cleavage | [001] Perfect; [100] Distinct |
| Fracture | Brittle |
| Mohs scale hardness | 2–2.5 |
| Luster | Vitreous; pearly |
| Streak | Pale green |
| Diaphaneity | Transparent to subtranslucent |
| Density | measured: 3.22; calculated: 3.264(1) |
| Optical properties | Uniaxial (−) |
| Refractive index | nω = 1.590 – 1.592 nε = 1.581 – 1.582 |
| Birefringence | δ = 0.009 – 0.010 |
| Pleochroism | Visible |
| Melting point | Decomposes before |
| Fusibility | Decomposes before |
| Other characteristics | Radioactive |
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.