ConchoidalGemdat.org, Management Team (2012), ConchoidalGemdat.org, Management Team (2012)
Subconchoidal, ConchoidalArthur Thomas, Gemstones (2009)
(Fe,Mg) 3Al 2(SiO 4) 3gemdat.org , Management Team (2012)
(Fe,Mn)Ta 2O 6Walter Schumann , Gemstones of the world (2001) More from other references