Uneven, Uneven, Gems, Sixth Edition (2006), Uneven, Conchoidal
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001)
NaAlSi 3O 8Michael OâDonoghue , Gems, Sixth Edition (2006)
Ca 2 MgAl 2 BSi 4 O 15 OH Gemdat.org, Management Team (2012)