UnevenWalter Schumann, Gemstones of the world (2001) More from other references, UnevenWalter Schumann, Gemstones of the world (2001) More from other references, Uneven
Subconchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle
(Zn,Fe)SMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Al2SiO4(F,OH)2