Uneven, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Conchoidal
Uneven, UnevenArthur Thomas, Gemstones (2009)
PbCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Cu 5(SiO 3) 4(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references