| Autunite | |
|---|---|
Autunite |
|
| General | |
| Category | Phosphate minerals |
| Chemical formula | Ca(UO2)2(PO4)2·10-12H2O |
| Strunz classification | 08.EB.05 |
| Identification | |
| Molar mass | 986.26 |
| Color | yellow - greenish fluorescent |
| Crystal system | tetragonal |
| Cleavage | {001} Perfect, {100} Poor, {010} Poor |
| Fracture | uneven |
| Mohs scale hardness | 2-2½ |
| Luster | vitreous - pearly |
| Streak | pale yellow |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 3.1-3.2 |
| Other characteristics | Radioactive |
Autunite (hydrated calcium uranyl phosphate) with formula: Ca(UO2)2(PO4)2·10-12H2O is a yellow - greenish fluorescent mineral with a hardness of 2 - 2½. Autunite crystallizes in the tetragonal system and often occurs as tabular square crystals. Due to the moderate uranium content of 48.27% it is radioactive and also used as uranium ore. If the mineral dries out, it converts to meta-autunite-I, which can turn into meta-autunite-II after heating. These two subsequent minerals are very rare in nature. For scientific studies it is recommended to store the mineral in a sealed container to minimize the water loss. Museums are known to have covered the mineral with lacquer to avoid drying of the mineral. Autunite was discovered in 1852 near Autun, France.
Some autunite is found near the Mount Spokane, Washington. 90,000 lbs of U3O8 were produced from nine properties, although most of the ore came from the Daybreak Mine. The digital geologic map of Spokane county and vicinity show where the autunite is extracted. Google earth: lat: 47.885306° long:-117.175846°