a common mineral, manganese dioxide, MnO2, the principal ore of manganese, used in various manufactures, as a decolouriser of brown or green tints in glass, as a depolariser in dry-cell batteries, etc.
a common mineral, manganese dioxide, MnO2, the principal ore of manganese, used in various manufactures, as a decolouriser of brown or green tints in glass, as a depolariser in dry-cell batteries, etc.