An important source of manganese

• A mineral consisting of manganese dioxide

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
"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 ).

WordNet Word definitions in WordNet
n. a mineral consisting of manganese dioxide; an important source of manganese

Wiktionary Word definitions in Wiktionary
n. (context mineralogy English) A dark coloured mineral, consisting of manganese dioxide (manganeseoxygen 2 ), that is an important ore of manganese.

Wikipedia Word definitions in Wikipedia
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 ...

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
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 ...