Tourmaline is a crystalline boron silicate mineral. Tourmaline is classified as a semi-precious stone and the gemstone comes in a wide variety of colors.

Brightly colored Ceylonese gem tourmalines were originally brought to Europe in great quantities by the Dutch East India Company.

Tourmaline was sometimes called the "Ceylonese Sri Lankan Magnet" because it could attract and then repel hot ashes due to its pyroelectric properties. Tourmalines were used by chemists in the 19th century to polarize light by shining rays onto a cut and polished surface of the gem.

Usually, iron-rich tourmalines are black to bluish-black to deep brown, while magnesium-rich varieties are brown to yellow, and lithium-rich tourmalines are almost any color including blue, green, red, yellow, & pink.

Multicolored crystals are common, reflecting variations of fluid chemistry during crystallization. Crystals may be green at one end and pink at the other, or green on the outside and pink inside; this type is called watermelon tourmaline. The pink color of tourmalines from many localities is the result of prolonged natural irradiation.

During the early 1900s, Maine and California were the world's largest producers of gem tourmalines. Gem and specimen tourmaline is mined chiefly in Brazil and Africa.

Tourmaline has recently been discovered in Tanzania, Nigeria, Kenya, Madagascar, Mozambique, Namibia, Afghanistan, India, Sri Lanka, and Malawi.

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