ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Gems, Sixth Edition (2006)
KNa 2(Fe3+ ,Mn3+ ,Al) 2Li 3Si 12O 30Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
SiO2 (with a high level of nickel impurities )