"Tourmaline ( /ˈtʊərməlɪn/, -/iːn/ TOOR-mə-lin, -leen) 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." - (en.wikipedia.org 05.10.2019)
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