Uneven, Subconchoidal, Uneven, Subconchoidal, Splintery, UnevenArthur Thomas, Gemstones (2009)
Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Good on {110}, poor on {100}
Perfect on [10 1 1] three directions with angle of 74° 55
Al 2SiO 5Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
CaCO 3Ulrich Henn and Claudio C.