Uneven, Splintery, Conchoidal, Uneven, Splintery, Conchoidal, UnevenWalter Schumann, Gemstones of the world (2001)
Subconchoidal, Conchoidal, Brittle, ConchoidalArthur Thomas, Gemstones (2009)
SiO 2Arthur Thomas , Gemstones (2009)
TiO 2Michael OâDonoghue , Gems, Sixth edition (2006) More from other references