noun 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.
noun 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.
Webster English vocab. Английский словарь Webster. 2012