sedimentary

Tumbled dark limestone or basalt with a pale mineral vein

Likely micritic limestone (calcite, CaCO₃), possibly basalt with a calcite/quartz vein

AI-generated identification · may be incorrect

Dark gray-black, rounded and polished, with a contrasting cream-white irregular vein or weathered rim. Estimated hardness 3 if calcitic limestone or 6 if basalt; dull to weakly waxy luster, no obvious crystals or cleavage visible.

Identified August 17, 2026More sedimentary →

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At a glance

Common name: Tumbled dark limestone or basalt with a pale mineral vein
Scientific name: Likely micritic limestone (calcite, CaCO₃), possibly basalt with a calcite/quartz vein
Category: sedimentary
Identified: August 17, 2026
Method: Standard

AI Estimated Value

About $1–$10 as a common tumbled or collected specimen; potentially $10–$25 if attractively polished and locally distinctive.

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

Formation & geological history

If limestone, it formed from compacted carbonate mud or shell material, commonly during the Paleozoic–Mesozoic; the pale band may be a calcite-filled fracture. If basalt, it formed from rapidly cooled lava, with the light material likely a secondary vein.

Uses & applications

Suitable as a decorative tumbled stone, craft piece, or teaching specimen; not generally valuable for jewelry or construction because of its small size and uncertain identity.

Geological facts

The specimen’s identity cannot be confirmed from the photograph alone; a drop of dilute hydrochloric acid or vinegar may fizz on exposed pale calcite, while basalt will not.

Field identification & locations

Look for a fine-grained black interior and test the light vein separately: calcite is relatively soft and reacts with acid, whereas quartz is harder and nonreactive. Common analogous material occurs in limestone quarries and basaltic volcanic regions worldwide.