Tourmaline  is a crystalline boron silicate mineral compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. Tourmaline is classified as a semi-precious stone and the gemstone comes in a wide variety of colors. The name comes from the Tamil and Sinhalese word “Turmali” (තුරමලි) or “Thoramalli” (තෝරමල්ලි), which applied to different gemstones found in Sri Lanka.

Credit : https://en.wikipedia.org/wiki/Tourmaline