Rock Identifier
Black spinel bead bracelet (Spinel (magnesium aluminate), MgAl₂O₄) — gemstone
gemstone

Black spinel bead bracelet

Spinel (magnesium aluminate), MgAl₂O₄

AI-generated identification · may be incorrect

Faceted black beads with vitreous luster; Mohs hardness 7.5–8, cubic crystal structure, no cleavage, and specific gravity about 3.6. The gold-colored links are jewelry hardware, not geological material.

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Physical properties

Faceted black beads with vitreous luster; Mohs hardness 7.5–8, cubic crystal structure, no cleavage, and specific gravity about 3.6. The gold-colored links are jewelry hardware, not geological material.

Formation & geological history

Natural spinel forms mainly in metamorphic carbonate rocks and alluvial deposits during high-temperature geological processes; gem-quality material commonly comes from Myanmar, Sri Lanka, Tanzania, Vietnam, and Cambodia. The beads are cut and polished from natural or possibly synthetic spinel.

Uses & applications

Used as a durable gemstone in bracelets, necklaces, and rings; black spinel is also marketed as an affordable alternative to black diamond or onyx.

Geological facts

Spinel is a distinct mineral, not a variety of corundum, despite frequently occurring alongside ruby and sapphire. Its strong durability and brilliant polish make it suitable for faceted beads.

Field identification & locations

Identify it by its glassy luster, high hardness, dense feel, and typically uniform black color; glass or dyed onyx may look similar. Exact identification requires refractive-index, density, or laboratory testing.