Uneven, Subconchoidal, Uneven, Subconchoidal, Splintery, UnevenArthur Thomas, Gemstones (2009)
Subconchoidal, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references
Good on {110}, poor on {100}
Octahedral, perfect on {111}, parting on {011}