The name “Paraiba” perks up the ears of people who like tourmaline. In 1989 and 1990, spectacular bright blue to bright green elbaite tourmaline, colored by trace amounts of copper, was found in pegmatite pockets at mines in the states of Paraiba and Rio Grande do Norte, Brazil. Later, violet specimens containing traces of both copper and manganese were found. The…

A table above lists the names and chemical compositions for 32 different members of the tourmaline mineral group. These names are based upon the chemical composition of the mineral. Because it can be impossible or impractical to determine the chemical composition of a large number of specimens or even a single specimen, the generic name…

Tourmaline is a complex boron silicate mineral with a generalized chemical composition of:XY3Z6(T6O18)(BO3)3V3W Letters in the formula above represent positions in the atomic structure of tourmaline that can be occupied by ions listed below.  X = Ca, Na, K, [] ([] = vacancy) Y = Li, Mg, Fe+2, Fe+3, Mn+2, Al, Cr+3, V+3 Z = Mg, Al,…

Tourmaline has a few properties that can aid in its identification. If you have a tourmaline crystal, identification should be easy. Don’t despair if your suspected tourmaline is an accessory mineral in an igneous or metamorphic rock. It often occurs in these rocks as tiny prismatic crystals. Get a hand lens and look for striations and rounded…

Brazil has been the world’s leading source of tourmaline for nearly 500 years. In the 1500s Portuguese explorers obtained green and blue tourmaline from indigenous people and from panning streams in search of gold. They thought that these colorful stones were emeralds and sapphires and sent them back to Portugal, where they were cut into gems and used to make jewelry…

The most common occurrence of tourmaline is as an accessory mineral in igneous and metamorphic rocks. It often occurs as millimeter-size crystals scattered through granite, pegmatite, or gneiss. In this mode of occurrence, tourmaline rarely makes up more than a few percent of the rock’s volume. The variety of tourmaline most often found as an accessory mineral is…

Tourmaline has a Mohs hardness of 7 to 7 ½, and that hardness makes it a durable sediment granule. Tourmaline is also relatively resistant to chemical weathering. So, particles of tourmaline weathered from igneous or metamorphic rocks can persist in a stream and can be transported long distances from their source area. Tourmaline gem rough is mined…

Tourmaline most commonly occurs as an accessory mineral in igneous and metamorphic rocks. Large, well-formed crystals of tourmaline can form in cavities and fractures during hydrothermal activity. Tourmaline is a hard and tenacious mineral. That enables it to persist during stream and beach transport as durable grains in sediments and sedimentary rocks. Tourmaline Crystals The most spectacular tourmaline…