Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Metallic
UnevenAnthony et al, Handbook of mineralogy (2001) More from other references, UnevenAnthony et al, Handbook of mineralogy (2001) More from other references, Brittle, Metallic
CuSMichael OâDonoghue , Gems, Sixth edition (2006) More from other references
CoAsSAnthony et al , Handbook of mineralogy (2001)