USA, Southern and central Africa, green, blue, China, India, USA, Italy, green, blue, China, India, USA, Italy
Southern and central Africa
White, Yellow
Yellow, Green, Blue, Violet
H 4Mg 3Si 2O 9Walter Schumann , Gemstones of the world (2001) More from other references
Al 2O 3Ulrich Henn and Claudio C.