Pyrolusite

n.

1.

(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).

Noun

1.

pyrolusite - a mineral consisting of manganese dioxide; an important source of manganese

atomic number 25, manganese, mineral, Mn