Uneven, UnevenArthur Thomas, Gemstones (2009), Conchoidal, Brittle
ConchoidalGemdat.org, Management Team (2012), ConchoidalGemdat.org, Management Team (2012)
(Na,Ca) 8Al 6Si 6O 24(SO 4,S,Cl) 2Ulrich Henn and Claudio C.
(Fe,Mg) 3Al 2(SiO 4) 3gemdat.org , Management Team (2012)