Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001)
ConchoidalArthur Thomas, Gemstones (2009)
Ca 2 MgAl 2 BSi 4 O 15 OH Gemdat.org, Management Team (2012)
MnTa 2O 6Walter Schumann , Gemstones of the world (2001) More from other references