A soft, black to dark gray mineral, MnO2 , the commonest and most important secondary ore of manganese.
A very soft, black, tetragonal mineral, MnO2, an ore of manganese used in making glass, paint, etc.; manganese dioxide.
Origin of pyrolusite
German Pyrolusit Greek puro- pyro- Greek lousis a washing (from louein to wash leu(ə)- in Indo-European roots)