mineral

Polished dark stone, likely labradorite or dark agate

Likely feldspar-rich labradorite (plagioclase) or microcrystalline quartz (chalcedony); exact identification requires testing

AI-generated identification · may be incorrect

Smooth tumbled/polished surface; dark brown-gray color with pale linear veining and subvitreous-to-waxy luster. Likely hardness 6–6.5 (labradorite) or about 7 (agate); no cleavage is visible.

Identified August 11, 2026More mineral →

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At a glance

Common name: Polished dark stone, likely labradorite or dark agate
Scientific name: Likely feldspar-rich labradorite (plagioclase) or microcrystalline quartz (chalcedony); exact identification requires testing
Category: mineral
Identified: August 11, 2026
Method: Standard

AI Estimated Value

Approximately $2–$15 for a common polished cabochon; $20–$75 if it displays strong labradorescence or distinctive natural patterning.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Smooth tumbled/polished surface; dark brown-gray color with pale linear veining and subvitreous-to-waxy luster. Likely hardness 6–6.5 (labradorite) or about 7 (agate); no cleavage is visible.

Formation & geological history

Labradorite forms in slowly cooled mafic igneous rocks, while agate forms as silica-filled cavities in volcanic rocks, commonly during the Precambrian to Phanerozoic. The specimen has been cut and polished.

Uses & applications

Used as a lapidary stone for cabochons, carvings, beads, and collectibles; not typically used in construction in this small polished form.

Geological facts

Labradorite commonly shows blue, green, or gold iridescent flashes, which are not obvious here; agate usually shows curved or concentric banding. A streak, hardness, and refractive-index test would distinguish them.

Field identification & locations

Common sources include Madagascar, India, Brazil, Mexico, and the United States. Check for feldspar cleavage and flash under angled light, or quartz-like hardness and waxy conchoidal fracture for agate.