Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle
Uneven, Yellow, White, UnevenWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Metallic
(Zn,Mn2+ )OMichael OâDonoghue , Gems, Sixth Edition (2006)
Ca2Al2Si3O12(OH)