UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Gems, Sixth Edition (2006), Gems, Sixth Edition (2006)
BaCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
SiO 2Michael OâDonoghue , Gems, Sixth Edition (2006)