Powellite

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For Enoch Powell, see here. For his political philosophy known as Powellism, see here.

Powellite
Category	Mineral Species
Chemical formula	CaMoO4
Identification
Molecular Weight	200.02 gm
Color	Yellow, brown, blue, black
Crystal habit	Massive to Crystaline
Crystal system	Tetragonal - Dipyramidal
Cleavage	Distinct on the [111]
Fracture	Conchoidal
Mohs Scale hardness	3.5-4
Luster	Adamantine
Refractive index	nω = 1.974 nε = 1.984
Optical Properties	Uniaxial (+)
Birefringence	δ = 0.010
Ultraviolet fluorescence	None
Streak	light yellow
Density	4.25 g/cm3
Diaphaneity	Transparent
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 in 1891 in the Peacock Mine, Adams County, Idaho and named for American explorer and geologist, John Wesley Powell (1834-1902).

[edit] References

1. ^ Powellite: Powellite mineral information and data
2. ^ Powellite Mineral Data

• 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