1) Mineral 
• (a.) A rare mineral having a velvet-black color and submetallic luster. It is a niobate of uranium, iron, and the yttrium and cerium metals.
Sa·mar'skite adjective [ After Samarski , a Russian.] (Min.) A rare mineral having a velvet-black color and submetallic luster. It is a niobate of uranium, iron, and the yttrium and cerium metals. 
[n] - a complex black mineral occuring in pegmatites
noun a complex black mineral occuring in pegmatites