Powellite
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For the political philosophy of Enoch Powell, see Powellism.
| Powellite | |
|---|---|
 Yellow-honey powellite crystal with colorless needles of scolecite, from Yeola, Nasik, Maharashtra, India (size: 108 x 75 mm, 272 g) | |
| General | |
| Category | Molybdate minerals |
| Formula (repeating unit) | CaMoO4 |
| Strunz classification | 07.GA.05 |
| Identification | |
| Formula mass | 200.02 g |
| Color | Yellow, brown, blue, black |
| Crystal habit | Massive to coarsely crystalline |
| Crystal system | Tetragonal - dipyramidal |
| Cleavage | Distinct on [111] |
| Fracture | Conchoidal |
| Mohs scale hardness | 3.5-4 |
| Luster | Adamantine |
| Streak | light yellow |
| Diaphaneity | Transparent |
| Density | 4.25 g/cm3 |
| Optical properties | Uniaxial (+) |
| Refractive index | nω = 1.974 nε = 1.984 |
| Birefringence | δ = 0.010 |
| Ultraviolet fluorescence | Fluoresces bright yellow under Shortwave ultraviolet light, dimmer under Longwave |
| References | [1][2] |
Powellite is a calcium molybdate mineral with formula CaMoO4. Powellite crystallizes with tetragonal - dipyramidal crystal structure as transparent adamantine blue, greenish brown, yellow to grey typically anhedral forms. It exhibits distinct cleavage and has a brittle to conchoidal fracture. It has a Mohs hardness of 3.5 to 4 and a specific gravity is 4.34. It forms a solid solution series with scheelite (calcium tungstate, CaWO4). It has refractive index values of nω=1.974 and nε=1.984.
Powellite was first described by William Harlow Melville in 1891 from the Peacock Mine, Adams County, Idaho and named for American explorer and geologist, John Wesley Powell (1834–1902).
References
- Palache, C., H. Berman, and C. Frondel (1951) Dana’s System of Mineralogy, (7th edition), v. II, pp. 1079–1081.
- Webmineral data
- Mindat with location data
- Mineral Data Publishing PDF
External links
Media related to Powellite at Wikimedia Commons
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