Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009)
Uneven, Irregular, Management Team (2012)
(Mg,Fe2+ )Al 2O 4Gemdat.org , Management Team (2012) More from other references
(Mg,Fe2+ ) 3Si 2O 5(OH) 4Anthony et al , Handbook of mineralogy (2001)