metamorphic

Greenstone (likely altered basalt or greenschist)

Greenschist-facies mafic rock; commonly chlorite–actinolite–albite ± epidote, or chlorite-altered basalt

AI-generated identification · may be incorrect

Fine-grained, dull green-gray, massive and weakly foliated with earthy to subvitreous luster. Typical hardness is about 5–6 Mohs; individual minerals are too fine-grained to confirm cleavage or crystals visually.

Identified September 5, 2026More metamorphic →

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At a glance

Common name: Greenstone (likely altered basalt or greenschist)
Scientific name: Greenschist-facies mafic rock; commonly chlorite–actinolite–albite ± epidote, or chlorite-altered basalt
Category: metamorphic
Identified: September 5, 2026
Method: Standard

AI Estimated Value

Approximately $1–$10 as an unproven common hand specimen; higher only with documented locality, unusual mineralogy, or attractive polish.

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

Probably basaltic volcanic rock altered by low-grade metamorphism or hydrothermal fluids, commonly during Paleozoic–Mesozoic tectonic events; exact age requires locality and laboratory analysis.

Uses & applications

Used locally as crushed aggregate, road stone, or decorative material; attractive dense pieces may be collected, but this rough specimen has little gem value.

Geological facts

“Greenstone” is a field term rather than one precise mineral or rock. Its green color commonly comes from chlorite, actinolite, epidote, or serpentine.

Field identification & locations

Look for a green-gray color, fine grain, compact texture, and subtle foliation; a streak, hardness test, acid test, thin section, or X-ray diffraction would help distinguish greenschist from altered basalt, serpentinite, or chlorite-rich shale. Common in ancient volcanic belts and metamorphic terrains.