USA, Southern and central Africa, green, blue, China, India, USA, Italy, green, blue, China, India, USA, Italy
Madagascar
H 4Mg 3Si 2O 9Walter Schumann , Gemstones of the world (2001) More from other references
LiNa(Zr,Ti,Hf)Si 6O 15Ulrich Henn and Claudio C.