UnevenWalter Schumann, Gemstones of the world (2001) More from other references, UnevenWalter Schumann, Gemstones of the world (2001) More from other references, Uneven
Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
(Zn,Fe)SMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Ca 3Al 2(SiO 4) 3Arthur Thomas , Gemstones (2009)