What is "pyrolusite"

Pyrolusite \Pyr`o*lu"site\, n. [Pyro- + Gr. ? to loose, or ? a loosing.] (Min.) Manganese dioxide, a mineral of an iron-black or dark steel-gray color and metallic luster, usually soft. Pyrolusite parts with its oxygen at a red heat, and is extensively used in discharging the brown and green tints of glass (whence its name).

"manganese dioxide," 1828, the name given in Roman times, when it was used, in a heated state, to de-colorize glass, from Greek elements pyro- "by heat, by fire" (see pyro-) + lysis "a loosening" (see lose).

n. (context mineralogy English) A dark coloured mineral, consisting of manganese dioxide (manganeseoxygen₂), that is an important ore of manganese.

n. a mineral consisting of manganese dioxide; an important source of manganese

Pyrolusite is a mineral consisting essentially of manganese dioxide ( Mn O) 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.