ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001)
SiO 2Ulrich Henn and Claudio C.
Ca 5(PO 4) 3FAnthony et al , Handbook of mineralogy (2001)