Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009)
ConchoidalGemdat.org, Management Team (2012), ConchoidalGemdat.org, Management Team (2012)
(Mg,Fe2+ )Al 2O 4Gemdat.org , Management Team (2012) More from other references
(Fe,Mg) 3Al 2(SiO 4) 3gemdat.org , Management Team (2012)