A basic oxide of aluminium, lithium, and manganese (Al,Li)MnO2(OH)2, found as bluish-black monoclinic crystals.

A mineral consisting of zirconium oxide (zirconia), occurring naturally as a minor constituent of some mafic igneous rocks and sometimes used as a…

= baddeleyite, n.

An oxide of titanium containing tantalum and ferric iron, found as black tetragonal crystals having a metallic lustre.

A silico-antimonate of bivalent manganese (partly replaced by magnesium and bivalent iron) and aluminium (partly replaced by trivalent iron)…

A strongly magnetic greyish black oxide of manganese, lead, and ferric iron occurring as acute dipyramidal crystals of the trigonal system.

A hydroxide and oxide of zinc, iron, magnesium, tin, and aluminium, crystallizing in the hexagonal system and occurring as brown or red…