Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001)
Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Metallic
Ca 2 MgAl 2 BSi 4 O 15 OH Gemdat.org, Management Team (2012)
CuSMichael OâDonoghue , Gems, Sixth edition (2006) More from other references