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
Spain, Brazil, USA, Sri Lanka, Burma, Color: strongly pleochroic, reddish brown, pink / yellowish green, Hardness: 7 7.5, Refractive index: 1.63 1.65, Density: 3.13 3.21, Chemical composition: Al2SiO5, Crystal structure: orthorhombic, Lustre: vitreous, greasy, Origins: Spain, Brazil, USA, Sri Lanka, Burma. Discovered in Andalusia (Spain), the andalusite stone is relatively rare, with big crystals over 10 ct. especially rare. Due to its remarkable pleochroism effect, the stone is highly valued by collectors., brown
Yellow
Brown, pink, Violet, Yellow, Green, White, gray, Colorless, Green, gray, Brown, Red
ConchoidalMichael OâDonoghue, Gems, Sixth Edition (2006), Gems, Sixth Edition (2006)
Uneven, Subconchoidal, Uneven, Subconchoidal, Splintery, UnevenArthur Thomas, Gemstones (2009)