COLUMBITE, a rare mineral consisting of iron niobate, in which the iron and niobium are replaced by varying amounts of manganese and tantalum respectively, the general for mula being (Fe, Mn) (Nb, It was in this mineral that Charles Hatchett discovered, in 18o1, the element niobium, which he himself called columbium after the country (Columbia or America) whence came the specimen in the British Museum col lection which he examined. It crystallizes in the orthorhombic system, and the black, opaque crystals are often very brilliant with a sub-metallic lustre. Hardness 6; sp. gr. 5.3. With increas ing amount of tantalum the specific gravity increases up to 7.3, and members at this end of the series have been given the name of tantalite These minerals occur as crystals and compact masses in granite and pegmatite.