UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
BaCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Al 2SiO 5Arthur Thomas , Gemstones (2009)