Tourmaline is a crystalline silicate mineral group in which boron is compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. Tourmaline is a gemstone and can be found in a wide variety of colors. Wikipedia
Color: Black, Green, Blue, Pink, Red, White, Yellow, Purple, Orange, Brown, Grey
Luster: Vitreous
Associated month: October
Crystal system: trigonal crystal system
Hardness (Mohs hardness scale): 7 – 7.5
Transparency: Opaque, Transparent
Refractive index: 1.616 – 1.65
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