Brazil, Southern and central Africa, Madagascar, Color: yellow, Hardness: 7, Refractive index: 1.54 1.55, Density: 2.65 2.66, Chemical composition: SiO2, Crystal structure: hexagonal, Origins: Widespread; best stones come from Brazil. Citrine is one of the least expensive gemstones. Even very big pieces, 50 carats and more, can be easily found on the market. Greenish-yellow and orange stones are more valuable, and heat treatment is often applied to enhance the yellow color., Yellow, brown, Yellow, brown, Yellow, brown, Yellow, brown, Yellow, brown, Yellow, brown, Yellow, brown, Yellow, brown, Yellow, brown, Yellow, brown
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.
ConchoidalMichael OâDonoghue, Gems, Sixth Edition (2006), Gems, Sixth Edition (2006)
Uneven, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Conchoidal, Brittle