Pyrolusite

Pyrolusite Dona Ana County, New Mexico, USA Miniature, 5.5 x 2.0 x 1.6 cm “Courtesy of Rob Lavinsky, The Arkenstone, www.iRocks.com”

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:

Pyrolusite Ilfeld, Harz Mts., Germany Small Cabinet, 7.7 x 6.3 x 2.7 cm “Courtesy of Rob Lavinsky, The Arkenstone, www.iRocks.com”
Pyrolusite Dona Ana County, New Mexico, USA Small Cabinet, 6.5 x 3.2 x 1.7 cm “Courtesy of Rob Lavinsky, The Arkenstone, www.iRocks.com”
Locality: Unnamed prospect, Tal-Tal, Antofagasta Region, Chile Source: Bob Jenkins Owner: RRUFF
Macro of a pyrolusite mineral with dendrite crystal formations. It is approximately 3 ½ inches (9 cm) tall. © Jonathan Zander
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