turmalin

Turmalin, known as tourmaline in English, is a family of crystalline boron silicate minerals that display a remarkable range of colors and chemical compositions. It crystallizes in the hexagonal system and often forms elongated, prismatic crystals. The mineral typically has a hardness of 7 to 7.5 on the Mohs scale and a specific gravity around 3.0. Tourmaline is strongly pleochroic, meaning it can show different colors when viewed from different directions, and it commonly occurs in layered, color-zoned crystals.

Color varieties within the tourmaline family are diverse. Elbaite is the most important gemstone species and can appear in pink, green, blue, yellow, brown, or multicolored stones. Rubellite refers to pink to red tourmaline, indicolite to blue, dravite to brown, and schorl to black. Paraíba tourmaline, prized for its neon blue to green hues, is copper-bearing and often originates from Brazil. The gem is frequently found in ingrown, gem-quality forms but can also occur in opaque or semi-opaque specimens.

Geologic occurrence and formation: tourmaline forms in granitic pegmatites and high-temperature metamorphic environments. It is commonly associated with quartz, feldspar, mica, and topaz. Major producing regions include Brazil, Afghanistan, Mozambique, Nigeria, Madagascar, Tanzania, Sri Lanka, and Pakistan, among others. Tourmaline’s wide color range and relative stability in heat contribute to its popularity as a gemstone and collector mineral.

Uses and care: tourmaline is widely used in jewelry and can command high value, particularly for rare colors like Paraíba or vivid indicolite. Treatments are variable and may include heating to alter or enhance color. For care, standard gemstone cleaning methods are advised; avoid harsh chemicals and differential heating that could affect some stones. In addition to its gem value, tourmaline is studied for its physical properties, such as piezoelectric and pyroelectric behavior.