Uneven, Uneven, Gemstones of the world (2001) More from other references
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001)
H 4Mg 3Si 2O 9Walter Schumann , Gemstones of the world (2001) More from other references
Ca 2 MgAl 2 BSi 4 O 15 OH Gemdat.org, Management Team (2012)