Tourmaline

Tourmaline (TUR-mə-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. The name comes from the Sinhalese word `Turmali` (තුරමලි) or `Thoramalli`...
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Tourmaline

• (n.) A mineral occurring usually in three-sided or six-sided prisms terminated by rhombohedral or scalenohedral planes. Black tourmaline (schorl) is the most common variety, but there are also other varieties, as the blue (indicolite), red (rubellite), also green, brown, and white. The red and green varieties when transparent are valued as j...
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tourmaline

<chemical> A mineral occurring usually in three-sided or six-sided prisms terminated by rhombohedral or scalenohedral planes. Black tourmaline (schorl) is the most common variety, but there are also other varieties, as the blue (indicolite), red (rubellite), also green, brown, and white. The red and green varieties when transparent are valued...
Found on http://www.encyclo.co.uk/local/20973

tourmaline

noun a mineral that is a complex borosilicate and hydroxide of aluminum containing iron and magnesium and calcium and lithium and sodium; it is usually black but occurs in transparent colored forms that are used as gemstones
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Tourmaline

Tour'ma·line noun [ French tourmaline , confer Italian turmalina , tormalina , New Latin turmalina , turmalinus ; all from tournamal , a name given to this stone in Ceylon.] (Min.) A mineral occurring usually in three-sided or six-sided prisms termina...
Found on http://www.encyclo.co.uk/webster/T/76

tourmaline

A semiprecious gemstone that is available in a wide range of colours, and that can appear to have more than one colour in itself. Tourmaline has a hardness of 7-7.5 on the Mohs Scale
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tourmaline

borosilicate mineral of complex and variable composition. Three types of tourmaline, distinguished by the predominance of certain elements, are ... [4 related articles]
Found on http://www.britannica.com/eb/a-z/t/66

tourmaline

Hard, brittle mineral, a complex silicate of various metals, but mainly sodium aluminium borosilicate. Small tourmalines are found in granites and gneisses. The common varieties range from black (schorl) to pink, and the transparent gemstones may be colourless (achromatic), rose pink (rubellite), green (Brazilian emerald), blue (indicolite, verdeli...
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Tourmaline

The tourmaline is a gemstone that contains in its composition various elements such as aluminium, iron, magnesium and sodium and therefore can come in many different colours ranging from black to shades of red, pink, blue, yellow or even lacking any color at all.
Found on https://www.encyclo.co.uk/local/22607

tourmaline

tourmaline (toor'mulin, –lēn) , complex borosilicate mineral with varying amounts of aluminum, iron, magnesium, sodium, lithium, potassium, and sometimes other elements, used as a gem. It occurs in prismatic crystals, commonly three-sided, six-sided, or nine-sided, and striated verti...
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Tourmaline

Tourmaline is the most commonly found in granite pegmatites. It is usually black in colour, but lighter coloured gem varieties are also found. It occurs usually in three-sided or six-sided prisms terminated by rhombohedral or scalenohedral planes. Black tourmaline (schorl) is the most common variety, but there are also other varieties, as the blue ...
Found on http://www.probertencyclopaedia.com/browse/HT.HTM

tourmaline

[n] - a mineral that is a complex borosilicate and hydroxide of aluminum containing iron and magnesium and calcium and lithium and sodium
Found on http://www.webdictionary.co.uk/definition.php?query=tourmaline
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