D defs.my
Entry 1 sense Webster, 1913

Pyrolusite

· Pyr·o·lu·site · IPA
01 n. Manganese dioxide, a mineral of an iron-black or dark steel-gray color and metallic luster, usually soft. Pyrolusite parts with its oxygen…
  1. 1.
    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).(Min.)