Uneven, Subconchoidal, Uneven, Subconchoidal, Splintery, UnevenArthur Thomas, Gemstones (2009)
Conchoidal, Brittle, Conchoidal
Good on {110}, poor on {100}
Good on [110] and on [001]
Al 2SiO 5Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
[ ]Na2(Mg3Al2)Si8O22(OH)2