Not Available, Southern and central Africa
USA, Southern and central Africa, green, blue, China, India, USA, Italy, green, blue, China, India, USA, Italy
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001)
Uneven, Uneven, Gemstones of the world (2001) More from other references
Ca 2 MgAl 2 BSi 4 O 15 OH Gemdat.org, Management Team (2012)
H 4Mg 3Si 2O 9Walter Schumann , Gemstones of the world (2001) More from other references