Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle
Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
Pb 5(AsO 4) 3ClMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
BaSO 4Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references