Brittle, Metallic, Brittle, Metallic
Conchoidal, Brittle, Conchoidal, UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
CaZnSiO 4 · H 2OAnthony et al , Handbook of mineralogy (2001)
CaSO 4Michael OâDonoghue , Gems, Sixth edition (2006) More from other references