Minerals identify

Know how to recognize them

Powellite

Molybdate mineral

Powellite is a calcium 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 4.25. It forms a solid solution series with scheelite (calcium tungstate, CaWO4). It has refractive index

Powellite was first described by William Harlow Melville in 1891 for an occurrence in the Peacock Mine, Adams County, Idaho and named for American explorer and geologist, John Wesley Powell

It occurs in hydrothermal deposits of molybdenum within the near surface oxidized zones. It also appears as a rare mineral phase in pegmatite and basalt. Minerals found in association with powellite include molybdenite, laumontite

Identification

Color of mineral

Yellow
Green
Brown
Blue
Black

Mohs scale ( mineral hardness )

3.5
4

The streak

Yellow

Density ( specific gravity )

1.974
1.984

Luster ( interacts light )

Adamantine

Crystal ( diaphaneity )

Tetragonal