Uneven, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Conchoidal
Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
PbCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
BaSO 4Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references