Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle
ConchoidalGemdat.org, Management Team (2012), ConchoidalGemdat.org, Management Team (2012)
(Be,Cs) 3Al 2Si 6O 18 · 0.5H 2OUlrich Henn and Claudio C.
(Fe,Mg) 3Al 2(SiO 4) 3gemdat.org , Management Team (2012)