Uneven, Conchoidal, Brittle, Metallic, ConchoidalArthur Thomas, Gemstones (2009)
Uneven, UnevenArthur Thomas, Gemstones (2009)
Ca 3Cr 2(SiO 4) 3Ulrich Henn and Claudio C.
Cu 5(SiO 3) 4(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references