ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
ZrO 2Arthur Thomas , Gemstones (2009)
SrSO 4Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references