Uneven, Uneven, Gems, Sixth Edition (2006)
UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
KAlSi 3O 8Michael OâDonoghue , Gems, Sixth Edition (2006)
Ca 2B 5SiO 9(OH) 5Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references