Rock Identifier
Tumbled dark stone, likely labradorite or serpentine (Likely labradorite (plagioclase feldspar; approximately NaAlSi₃O₈–CaAl₂Si₂O₈) or serpentine-group mineral) — mineral
mineral

Tumbled dark stone, likely labradorite or serpentine

Likely labradorite (plagioclase feldspar; approximately NaAlSi₃O₈–CaAl₂Si₂O₈) or serpentine-group mineral

AI-generated identification · may be incorrect

Dark gray-green, rounded and polished, with pale bluish reflective patches; likely Mohs 4–6, vitreous to waxy luster, and no visible cleavage in the tumbled form. Identification is uncertain from the photograph alone.

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Physical properties

Dark gray-green, rounded and polished, with pale bluish reflective patches; likely Mohs 4–6, vitreous to waxy luster, and no visible cleavage in the tumbled form. Identification is uncertain from the photograph alone.

Formation & geological history

Labradorite forms in mafic igneous rocks such as basalt and gabbro; serpentine forms by hydrothermal alteration of ultramafic rocks. Both are geologically ancient and occur in many Precambrian and younger terrains.

Uses & applications

Used as a cabochon, tumbled stone, ornamental material, and metaphysical collectible; labradorite is especially valued for blue-green schiller (labradorescence).

Geological facts

Strong blue flash under angled light would favor labradorite; a softer waxy appearance and green-black mottling would favor serpentine. The specimen appears human-tumbled and polished.

Field identification & locations

Common sources include Madagascar, Finland, Canada, Russia, and the United States for labradorite, while serpentine is widespread in ophiolite belts. Test carefully for hardness and inspect flashes under a focused light.