出典:Wiktionary
出典:Wikipedia
出典:『Wikipedia』 (2011/06/17 20:44 UTC 版)
Columbite, also called niobite, niobite-tantalite and columbate [(Fe, Mn)(Nb, Ta)2O6], is a black mineral group that is an ore of niobium and tantalum. It has a submetallic luster and a high density and is 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 manganocolumbite. The iron-rich member of the columbite group is ferrocolumbite. Some tin and tungsten may be present in the mineral. Yttrocolumbite is the yttrium-rich columbite with the formula (Y,U,Fe)(Nb,Ta)O4. It is a radioactive mineral found in Mozambique.