mineral
Black tourmaline bead bracelet (likely schorl)
Schorl, NaFe²⁺₃Al₆(BO₃)₃Si₆O₁₈(OH)₄
AI-generated identification · may be incorrectOpaque black, vitreous-to-waxy luster; tourmaline is trigonal and has Mohs hardness 7–7.5, with no cleavage and characteristic strong striations. The beads appear polished and may show inclusions or surface fractures.
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Physical properties
Opaque black, vitreous-to-waxy luster; tourmaline is trigonal and has Mohs hardness 7–7.5, with no cleavage and characteristic strong striations. The beads appear polished and may show inclusions or surface fractures.
Formation & geological history
Forms mainly in boron-rich granitic pegmatites and hydrothermal veins, crystallizing during late-stage magma cooling, commonly in the Paleozoic to younger geological record. Major sources include Brazil, Afghanistan, Pakistan, Madagascar, and the United States.
Uses & applications
Cut and polished into beads, cabochons, and ornamental objects; black tourmaline is popular in mineral collections and metaphysical jewelry. It has limited industrial use compared with other tourmaline varieties.
Geological facts
Tourmaline is piezoelectric and can develop electrical charge when heated or compressed. Schorl is the most common tourmaline species and is not the same as glossy black glass or jet.
Field identification & locations
Likely geological material because of the bead texture and reflective polished surfaces, though the photograph cannot confirm composition; glass or dyed stone are alternatives. Tourmaline is identified by hardness, lack of cleavage, striated crystals, and electrical effects when tested carefully.
