UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
Brittle, Metallic
Ca 2(Mg,Al) 6(Si,Al,B) 6O 20Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
CaCuAlSi 2O 6(OH) 3Michael OâDonoghue , Gems, Sixth Edition (2006)