Manganese oxide.

Any of various kinds of brown stone (typically sandstone) used for building; esp. a dark reddish-brown sandstone formerly widely used in the…

Mineralogy. Basic manganese oxide, MnO(OH), a monoclinic mineral which occurs as dark grey or black prismatic crystals and fibrous masses and is an…

An anhydrous oxide of manganese, a brittle dark brownish-black mineral occurring both crystallized and massive.

Containing manganese in the divalent state and in one of its higher valencies; only in manganoso-manganic oxide n. = mangano-manganic oxide at man…

(see quot.).

each of the six oxides of manganese; esp. = manganese dioxide n.

Manganese oxide, MnO, a cubic mineral occurring as translucent green octahedral crystals which blacken on exposure to air.

An orthorhombic oxide of manganese, antimony, and arsenic, occurring as small black grains in certain metamorphic rocks in Sweden.