ConchoidalWalter Schumann, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references
Uneven, UnevenArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Not Available
(Na,Ca) 8Al 6Si 6O 24(SO 4,S,Cl) 2Ulrich Henn and Claudio C.