Uneven, UnevenArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Gems, Conchoidal, Brittle
(Na,Ca) 8Al 6Si 6O 24(SO 4,S,Cl) 2Ulrich Henn and Claudio C.
Ca 3Ti4+2(Fe3+2Si)O 12Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references