USA, Southern and central Africa, green, blue, China, India, USA, Italy, green, blue, China, India, USA, Italy
Not Available, Southern and central Africa
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)