metamorphic

Greenstone (likely chlorite- or actinolite-rich metabasalt)

Metamorphosed mafic volcanic rock; commonly greenschist-facies basalt, composed chiefly of chlorite, actinolite, epidote, and albite

AI-generated identification · may be incorrect

Dark green-gray, fine-grained and dull, with a rough, uneven surface and possible foliation; hardness and density vary with mineral content. The photo does not show enough detail for a definitive mineral or crystal-structure identification.

Identified October 4, 2026More metamorphic →

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At a glance

Common name: Greenstone (likely chlorite- or actinolite-rich metabasalt)
Scientific name: Metamorphosed mafic volcanic rock; commonly greenschist-facies basalt, composed chiefly of chlorite, actinolite, epidote, and albite
Category: metamorphic
Identified: October 4, 2026
Method: Standard

AI Estimated Value

About $2–$20 for a common hand specimen; higher value generally requires distinctive mineralization, provenance, or display quality.

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

Typically forms when basalt or similar mafic rock is altered by low-grade regional metamorphism and hydrothermal fluids. Its age and specific formation environment cannot be determined from the image.

Uses & applications

Used locally as building or landscaping stone and collected as a geological specimen; this piece appears unworked beyond natural weathering or breakage.

Geological facts

“Greenstone” is a descriptive field term rather than a single precise rock composition; its green color commonly comes from chlorite, actinolite, or epidote.

Field identification & locations

Look for a dense, dark-green rock with fine grains and, in some specimens, weak foliation; confirm with a fresh surface and mineral tests. Greenstone belts occur worldwide, but locality cannot be inferred from this image.