Columbite

from WordNet (r) 3.0 (2006)

columbite
    n 1: a black mineral that is an ore of niobium and tantalum
         [syn: {niobite}, {columbite}]

from The Collaborative International Dictionary of English v.0.48

Columbite \Co*lum"bite\, n. [Cf. F. colombite. See {Columbium}.]
   (Min.)
   A mineral of a black color, submetallic luster, and high
   specific specific gravity. It is a niobate (or columbate) of
   iron and manganese, containing tantalate of iron; -- first
   found in New England.
   [1913 Webster]