Pyrolusite | |
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General | |
Category | Oxide minerals |
Formula (repeating unit) | MnO2 |
IMA symbol | Pyl[1] |
Strunz classification | 4.DB.05 |
Crystal system | Tetragonal |
Crystal class | Ditetragonal dipyramidal (4/mmm) H-M symbol: (4/m 2/m 2/m) |
Space group | P42/mnm |
Identification | |
Color | Darkish, black to lighter grey, sometimes bluish |
Crystal habit | Granular to massive: botryoidal. Crystals rare |
Twinning | {031}, {032} may be polysynthetic |
Cleavage | Perfect on 110 |
Fracture | Irregular/Uneven |
Tenacity | Brittle |
Mohs scale hardness | 6–6.5, 2 when massive |
Luster | Metallic, dull to earthy |
Streak | Black to bluish-black |
Specific gravity | 4.4–5.06 |
Refractive index | Opaque |
References | [2][3][4][5] |
Major varieties | |
Polianite | pseudomorphic after manganite[6] |
Pyrolusite is a mineral consisting essentially of manganese dioxide (MnO2) and is important as an ore of manganese.[7] It is a black, amorphous appearing mineral, often with a granular, fibrous, or columnar structure, sometimes forming reniform crusts. It has a metallic luster, a black or bluish-black streak, and readily soils the fingers. The specific gravity is about 4.8. Its name is from the Greek for fire and to wash, in reference to its use as a way to remove tints from glass.[5]