GALLIUM - (n.) A rare metallic element, found combined in certain zinc ores. It is white, hard, and malleable, resembling aluminium, and remarkable for its low melting point (86Ў F., 30Ў C.). Symbol, Ga; at. wt., 69.9. Gallium is chiefly trivalent, resembling aluminium and indium. It was predicted with most of its properties, under the name eka-aluminium, by Mendelyeev on the basis of the periodic law. This prediction was verified in its discovery (in 1875) by its characteristic spectrum (two violet lines).