a mineral that is a source of rare earths; consists of silicates of iron and beryllium and cerium and yttrium and erbium
A dark, vitreous mineral that is a complex mixture of silicates of cerium, lanthanum, neodymium, yttrium, beryllium, and iron, with the chemical formula (Ce,La,Nd,Y)₂FeBe₂Si₂O₁₀.