UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Metallic
Na 8Al 6Si 6O 24Cl 2Michael OâDonoghue , Gems, Sixth Edition (2006)
PbCa 3Zn 4(SiO 4) 4Anthony et al , Handbook of mineralogy (2001)