ConchoidalWalter Schumann, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Metallic
Uneven, Subconchoidal, Uneven, Subconchoidal, Splintery, UnevenArthur Thomas, Gemstones (2009)
Perfect on {010}, good on {100}
Good on {110}, poor on {100}
Be 2BO 3(OH)Ulrich Henn and Claudio C.
Al 2SiO 5Michael OâDonoghue , Gems, Sixth edition (2006) More from other references