Irregular/uneven, Brittle, Metallic
Uneven, Subconchoidal, Uneven, Subconchoidal, Splintery, UnevenArthur Thomas, Gemstones (2009)
Ca6(Al,Si)2(SO4)2B(OH)4(OH,O)12•26(H2O)
Al 2SiO 5Michael OâDonoghue , Gems, Sixth edition (2006) More from other references