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 2 MgAl 2 BSi 4 O 15 OH Gemdat.org, Management Team (2012)