Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Metallic
Subconchoidal, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Mg 2Si 2O 6Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
CaBePO 4(F,OH)Ulrich Henn and Claudio C.