UnevenWalter Schumann, Gemstones of the world (2001) More from other references, UnevenWalter Schumann, Gemstones of the world (2001) More from other references, Uneven
Splintery, UnevenArthur Thomas, Difficult, Fibrous
(Zn,Fe)SMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
NaAlSi 2O 6Ulrich Henn and Claudio C.