UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
Conchoidal, Splintery, Fibrous, UnevenArthur Thomas, Gemstones (2009)
Na 8Al 6Si 6O 24Cl 2Michael OâDonoghue , Gems, Sixth Edition (2006)
CaSO 4 -2(H 2O)Arthur Thomas , Gemstones (2009)