ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Uneven, UnevenArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Ca 5(F,Cl)(PO 4) 3Arthur Thomas , Gemstones (2009)
(Na,Ca) 8Al 6Si 6O 24(SO 4,S,Cl) 2Ulrich Henn and Claudio C.