mineral

Black tourmaline beads (likely schorl)

Schorl, NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄

AI-generated identification · may be incorrect

Opaque black, vitreous-to-resinous luster, commonly trigonal-prismatic crystal structure; Mohs hardness 7–7.5, specific gravity about 3.1–3.3, with indistinct cleavage. The beads are polished and drilled, so natural crystal faces are absent.

Identified August 13, 2026More mineral →

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Physical properties

Formation & geological history

Forms mainly in granite pegmatites and hydrothermal veins during late-stage igneous activity; specimens range from Precambrian to younger geologic ages. The image shows a human-processed gemstone strand rather than raw material.

Uses & applications

Used for jewelry, beads, carvings, and mineral collecting; its durability and intense black color make it popular in bracelets and necklaces.

Geological facts

Schorl is the most common tourmaline species and is valued for strong pleochroism and electrical properties when heated or pressed. Black tourmaline is often marketed as a protective or grounding stone, though such claims are not scientifically established.

Field identification & locations

Identify it by its deep black color, high polish, moderate heaviness, and glassy luster; genuine tourmaline is usually harder than glass and may show subtle longitudinal striations before polishing. Common sources include Brazil, Africa, Afghanistan, Pakistan, and the United States.