Uneven, Uneven, Gemstones of the world (2001) More from other references
UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
H 4Mg 3Si 2O 9Walter Schumann , Gemstones of the world (2001) More from other references
Na 8Al 6Si 6O 24Cl 2Michael OâDonoghue , Gems, Sixth Edition (2006)