Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Metallic
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
CuSMichael OâDonoghue , Gems, Sixth edition (2006) More from other references
SrCO 3Walter Schumann , Gemstones of the world (2001) More from other references