fergusonite
  褐釔鈮礦
  Fer·gu·son·ite n. Min. A mineral of a brownish black color, essentially a tantalo-niobate of yttrium, erbium, and cerium; -- so called after Robert Ferguson.
  ◄ ►
  fergusonite
       n : a dark mineral consisting of oxides of yttrium and erbium
           and tantalum and other minerals