Splintery, UnevenArthur Thomas, Difficult, Fibrous
UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
NaAlSi 2O 6Ulrich Henn and Claudio C.
Ca 2(Mg,Al) 6(Si,Al,B) 6O 20Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references