ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Uneven
Uneven, Brittle, Metallic, Brittle, Metallic, Brittle, Metallic
(Al,Mg) 8(Al,Si) 6O 20Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
(Na,Fe,Ca)Si 2O 6Ulrich Henn and Claudio C.