samarskite

A velvet-black mineral that is a complex mixture of several rare-earth metals with niobium and tantalum oxide.

A niobate of uranium, iron, and manganese, of a velvet-black color, submetallic luster, and conchoidal fracture.

A rare mineral having a velvet-black color and submetallic luster. It is a niobate of uranium, iron, and the yttrium and cerium metals.

A shiny black radioactive mineral that contains a complex mixture of rare earth oxides

a complex black mineral occurring in pegmatites