Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009)
Uneven, UnevenArthur Thomas, Gemstones (2009), Conchoidal, Brittle
(Mg,Fe2+ )Al 2O 4Gemdat.org , Management Team (2012) More from other references
(Na,Ca) 8Al 6Si 6O 24(SO 4,S,Cl) 2Ulrich Henn and Claudio C.