Columbite, also called niobite, niobite-tantalite, columbate and columbite [(Fe, Mn)(Nb, Ta)2O6]'s a black mineral group that's an ore of niobium and tantalum. It's a submetallic luster and a high specific gravity and's a niobate of iron and manganese, containing tantalate of iron. This mineral group was first found at Haddam, Middlesex County, Connecticut in New England, USA. It forms a series with the tantalum-dominant analogue ferrotantalite and one with the manganese-dominant analogue manga… (More on Columbite)