Brittle, Metallic
Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
CaCuAlSi 2O 6(OH) 3Michael OâDonoghue , Gems, Sixth Edition (2006)
Mg 3B 7O 13ClMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references