metamorphic

Likely greenstone (chlorite/epidote-altered basalt), waterworn pebble

Greenschist-facies metabasalt; commonly composed of chlorite, actinolite, epidote, and albite

AI-generated identification · may be incorrect

Dark green-gray, fine-grained and mottled, with pale mineral flecks and a dull to slightly vitreous luster. Typical greenschist minerals are Mohs 5–6; the photo does not establish the specimen’s exact hardness or mineral identity.

Identified October 11, 2026More metamorphic →

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At a glance

Common name: Likely greenstone (chlorite/epidote-altered basalt), waterworn pebble
Scientific name: Greenschist-facies metabasalt; commonly composed of chlorite, actinolite, epidote, and albite
Category: metamorphic
Identified: October 11, 2026
Method: Standard

AI Estimated Value

About $1–$10 for a common, unverified pebble; more if its locality or composition is documented.

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

Likely basalt altered by low-grade metamorphism and fluids, then rounded by transport in water. Metamorphic age and precise formation environment cannot be determined from the image.

Uses & applications

Greenstone is used as decorative or carving stone and occasionally as aggregate; this small pebble is mainly suitable for collecting.

Geological facts

“Greenstone” is a field name for green, altered mafic rock rather than a single mineral or precisely defined rock composition.

Field identification & locations

The rounded shape suggests stream or beach transport; look for a dense, fine-grained green matrix with scattered pale epidote or feldspar. Similar rocks occur in ancient volcanic and metamorphic belts worldwide.