Aegirine

Aegirine belongs to the silicate group. It contains sodium, iron _, and silicon. It _is a sodium iron silicate. Its chemical formula is ^{NaFe³⁺Si₂O₆} . Aegirine typically occurs as prismatic or acicular crystals with a striated and lustrous appearance. Aegirine is most often black, but it can also be found in brown or green crystals. Its density is greater than 3.5 (compared to 1 for water), and its hardness is 6/10 on the Mohs scale (compared to 10 for diamond). The streak on porcelain is predominantly green. The name Aegirine comes from the name of the Norse mythological god Aegir.