USA, Mexico, Brazil, Switzerland, Sri Lanka, Burma, Madagascar, Color: colorless, light yellow, light pink, Hardness: 7, Refractive index: 1.63 1.64, Density: 2.98 3.03, Chemical composition: Ca(B2Si2O8), Crystal structure: orthorhombic, Origins: USA, Mexico, Brazil, Germany, Switzerland, Sri Lanka, Burma, Madagascar, Japan. Colorless danburites are common, with light pink or yellowish stones being more rare and expensive. Only eye clean pieces are valuable.
Southern and central Africa
Yellow, Brown, Colorless, White, gray, Brownish, Yellow
Blue
Uneven, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Conchoidal, Brittle
Not Available
CaB 2(SiO 4) 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
SrTiO 3Gemdat.org , Management Team (2012)