mineral

Polished black tourmaline pendant (probable)

Schorl tourmaline, NaFe3Al6(BO3)3Si6O18(OH)4

AI-generated identification · may be incorrect

Glossy black to blue-black, vitreous luster, likely polished and drilled/carved; Mohs hardness 7–7.5, trigonal crystal structure, no obvious cleavage, specific gravity about 3.0–3.3. The image cannot confirm composition, and it could instead be polished obsidian or another dark stone.

Identified September 4, 2026More mineral →

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Physical properties

Formation & geological history

Black tourmaline forms in granitic pegmatites and hydrothermal veins as elongated prismatic crystals, commonly during late-stage crystallization of felsic magma. Most gem-quality material is geologically young relative to Earth’s history, with ages depending on its host granite or pegmatite.

Uses & applications

Used for pendants, beads, cabochons, mineral specimens, and ornamental carvings; industrial tourmaline has limited specialized uses. Common polished pieces generally have modest value.

Geological facts

Tourmaline is strongly pleochroic and often piezoelectric: heating or pressure can produce electrical charges. Schorl is the common iron-rich black variety.

Field identification & locations

Check for a long, prismatic crystal habit, faint lengthwise striations, and attraction to charged dust; tourmaline is usually less uniformly glassy than obsidian. Common sources include Brazil, Afghanistan, Pakistan, Namibia, Madagascar, and the United States.