Columbite, also called niobite, niobite-tantalite and columbate, with a general chemical formula of Nb2O6, is a black mineral group that is an ore of niobium. It has a submetallic luster, a high densi

Coltan is a dull black metallic ore from which the elements niobium and tantalum are extracted. The niobium-dominant mineral in coltan is columbite, and the tantalum-dominant mineral is tantalite.