Hypertext Webster Gateway: "pyrolusite"
From Webster's Revised Unabridged Dictionary (1913) (web1913)
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).
From WordNet (r) 1.7 (wn)
pyrolusite
n : a mineral consisting of manganese dioxide; an important
source of manganese
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