mineral
Black stone bead bracelet
Likely black tourmaline (schorl), though identification is uncertain from the image
AI-generated identification · may be incorrectOpaque black, dull to subvitreous luster, commonly striated prismatic crystals; Mohs hardness 7–7.5, brittle, specific gravity about 3.0–3.3. The beads appear polished and rounded, obscuring diagnostic crystal form.
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Physical properties
Opaque black, dull to subvitreous luster, commonly striated prismatic crystals; Mohs hardness 7–7.5, brittle, specific gravity about 3.0–3.3. The beads appear polished and rounded, obscuring diagnostic crystal form.
Formation & geological history
If tourmaline, it formed in boron-rich granitic pegmatites and hydrothermal veins, generally during the Mesozoic or younger depending on locality. Other possibilities include black obsidian, onyx, hematite, or dyed stone.
Uses & applications
Used as ornamental beads, jewelry, carvings, and mineral specimens; black tourmaline is also popular in metaphysical products. It has little industrial use in this bead form.
Geological facts
Schorl is the most common tourmaline species and may show strong electrical polarization when heated or rubbed (the tourmaline effect).
Field identification & locations
Test with a loupe for elongated striations or fibrous texture; tourmaline is harder than steel and glass, but hardness testing may damage jewelry. Exact identification requires an individual bead, streak, density, or laboratory analysis.
