Chemical Formula: MnO2
Name Origin: From the Greek, pyro and louein, “fire” and “to wash,” because it was used to remove the greenish color imparted to glass by iron compounds.
Pyrolusite is a mineral consisting essentially of manganese dioxide (MnO2) and is important as an ore of manganese. 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.
History
Authors : HAIDINGER
Discovery date : 1827
Optical properties
Optical and misc. Properties : Fragile, cassant –  Opaque –  Macles possibles –
Reflective Power: HAUT
Physical Properties
Hardness: from 6,00 to 6,50
Density : 5,06
Color : steel grey; black
Luster: metallic; unpolished
Streak : black; bluish black
Cleavage : yes
Photos:
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