Black Tourmaline

Hardness: 7-7.5 on Mohs scale. Color: Opaque black. Luster: Vitreous to resinous. Crystal structure: Trigonal; often found in prismatic crystals with vertical striations. Cleavage: Indistinct. Specific Gravity: 3.1-3.2.

Black Tourmaline (Schorl) forms in igneous and metamorphic rocks. It's commonly found in granite pegmatites, granites, and schists, often crystallizing from hot hydrothermal solutions. Its formation is typically associated with late-stage crystallization in magmatic and contact metamorphic environments. Geological age varies widely, from Precambrian to recent, depending on the specific geological setting.

Black Tourmaline is highly valued in the gemstone and jewelry industry, often cut into cabochons, beads, and faceted stones. It's also used as a carving material. In industry, it can be used in pressure-sensitive gauges (piezoelectric properties) though synthetic materials are more common for this. It's very popular in metaphysical and crystal healing practices.

Black Tourmaline is the most common variety of Tourmaline, accounting for about 95% of all natural tourmaline. It's known for its strong protective and grounding properties in various traditions. It can exhibit pyroelectricity (generating an electrical charge when heated) and piezoelectricity (generating an electrical charge when pressure is applied).

In the field, Black Tourmaline is identified by its opaque black color, prismatic crystal habit with vertical striations, and often a somewhat rough, fibrous appearance on broken surfaces. Its hardness helps distinguish it from softer black minerals. It is commonly found in Brazil, Pakistan, Afghanistan, Africa (Madagascar, Namibia), and the USA (California, Maine). Collectors often look for well-formed crystals, particularly those with good luster. It feels relatively dense for its size.