USA, Southern and central Africa, green, blue, China, India, USA, Italy, green, blue, China, India, USA, Italy
Southern and central Africa
H 4Mg 3Si 2O 9Walter Schumann , Gemstones of the world (2001) More from other references
(Mg,Fe2+ ) 5Al(Si 3Al)O 10(OH) 8Anthony et al , Handbook of mineralogy (2001)