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