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