Uneven, Subconchoidal, Uneven, Subconchoidal, Splintery, UnevenArthur Thomas, Gemstones (2009)
Brittle, Metallic, Brittle, Metallic
Al 2SiO 5Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
CaZnSiO 4 · H 2OAnthony et al , Handbook of mineralogy (2001)