Clarkeite
Clarkeite | |
---|---|
General | |
Category | Mineral |
Formula (repeating unit) | (Na,Ca,Pb) 2(UO 2) 2(O,OH) 3 or (Na,Ca,Pb)(UO 2)O(OH)•0-1H 2O |
IMA symbol | Cke[1] |
Strunz classification | 4.GC.05 |
Dana classification | 5.4.1.1 |
Crystal system | Trigonal |
Space group | R3m (No. 166) |
Unit cell | 239.11 ų (Calculated from Unit Cell) |
Identification | |
Colour | Dark red-brown, dark brown |
Cleavage | None observed |
Fracture | Conchoidal, Sub-Conchoidal |
Mohs scale hardness | 4-4.5 |
Luster | Resinous, Waxy, Greasy |
Streak | Yellow-brown |
Diaphaneity | Translucent |
Specific gravity | 6.39 |
Density | 6.39 g/cm3 (Measured) |
Birefringence | 0.111 |
Pleochroism | Weak |
2V angle | Measured 30° to 50°, Calculated 32° |
Dispersion | Relatively weak |
Other characteristics | ![]() |
Clarkeite is a uranium oxide mineral with the chemical formula(Na,Ca,Pb)
2(UO
2)
2(O,OH)
3 or (Na,Ca,Pb)(UO
2)O(OH)•0-1H
2O.
Its color varies from dark brown to reddish orange. Clarkeite forms by oxidation and replacement of uraninite late during pegmatite crystallization. Although uraninite-bearing granite pegmatites are common, clarkeite is rare and occurs intimately intergrown with other uranium minerals.
It is known from only two localities; the Spruce Pine pegmatite district in western North Carolina, US, and Rajputana, in the Ajmer district, India. Clarkeite is the only known naturally occurring high-temperature uranate. The general formula for ideal clarkeite is Na[(UO
2)O(OH)](H
2O)
0–1.
It was named for Frank Wigglesworth Clarke (1847–1931), American mineral chemist, and former chief chemist of the United States Geological Survey.
See also[]
- List of minerals
- List of minerals named after people
- Sodium uranate
References[]
- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- Clarkeite: New chemical and structural data
- Clarkeite: Clarkeite mineral information and data
- WebMineral
- Uranium minerals
- Sodium minerals
- Hydroxide minerals
- Trigonal minerals
- Minerals in space group 166
- Oxide mineral stubs
- Oxide minerals