Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
ConchoidalGemdat.org, Management Team (2012), ConchoidalGemdat.org, Management Team (2012)
SiCArthur Thomas , Gemstones (2009)
(Fe,Mg) 3Al 2(SiO 4) 3gemdat.org , Management Team (2012)