Conchoidal, Brittle, Conchoidal, UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009)
CaSO 4Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
(Mg,Fe2+ )Al 2O 4Gemdat.org , Management Team (2012) More from other references