Brittle, Metallic
UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Uneven
CaCuAlSi 2O 6(OH) 3Michael OâDonoghue , Gems, Sixth Edition (2006)
FeS 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references