ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Uneven
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
(Al,Mg) 8(Al,Si) 6O 20Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Na 2(Ti,Fe)Si 4(O,F) 11Ulrich Henn and Claudio C.