ConchoidalGemdat.org, Management Team (2012), ConchoidalGemdat.org, Management Team (2012)
Uneven, Uneven, Gemstones of the world (2001) More from other references
(Fe,Mg) 3Al 2(SiO 4) 3gemdat.org , Management Team (2012)
Ca 10Mg 2Al 4(SiO 4) 5(Si 2O 7) 2(OH) 4Ulrich Henn and Claudio C.