a blackish fibrous or soft powdery mineral consisting of manganese dioxide in tetragonal crystalline form. It occurs in association with other manganese ores and is an important source of manganese. Formula: MnO2
Word origin
C19: from pyro- + Greek lousis a washing +-ite1, from its use in purifying glass
pyrolusite in American English
(ˌpaɪroʊˈluˌsaɪt; paɪˈrɑljuˌsaɪt)
noun
a very soft, black, tetragonal mineral, MnO2, an ore of manganese used in making glass, paint, etc.; manganese dioxide
Word origin
Ger pyrolusit < Gr pyr, fire + lousis, a washing (< louein, to wash < IE base *lou-, to wash > lather) + Ger -it, -ite1: used, when heated, to remove color from glass