ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
Uneven, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
SiO 2Ulrich Henn and Claudio C.
Ca 3Al 2(SO 4)(F,OH) 10Ulrich Henn and Claudio C.