pyrolusite

Pyr`o*lu"site, n. Etym: [Pyro- + Gr. (Min.) Defn: 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).

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