Uneven, Uneven, Gemstones of the world (2001) More from other references
Gems, Sixth Edition (2006), Gems, Sixth Edition (2006)
H 4Mg 3Si 2O 9Walter Schumann , Gemstones of the world (2001) More from other references
SiO 2Michael OâDonoghue , Gems, Sixth Edition (2006)