metamorphic

Greenstone / altered basalt (probable)

Chlorite–epidote–actinolite-rich metabasalt; exact identification requires testing

AI-generated identification · may be incorrect

Dark green-gray, mottled, fine-grained, and dull to slightly waxy; likely hardness about 5–6, with no obvious cleavage and a dense, compact texture. The pale green matrix may contain chlorite, epidote, actinolite, or serpentine.

Identified September 14, 2026More metamorphic →

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At a glance

Common name: Greenstone / altered basalt (probable)
Scientific name: Chlorite–epidote–actinolite-rich metabasalt; exact identification requires testing
Category: metamorphic
Identified: September 14, 2026
Method: Standard

AI Estimated Value

About $1–$15 for a small ordinary specimen; $20–$100 or more if it proves to be attractive jade, high-quality serpentine, or a documented collectible locality.

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 formed when basaltic lava undergoes low-grade metamorphism or hydrothermal alteration, commonly in ancient oceanic crust and volcanic belts. Geological age cannot be determined from the photograph.

Uses & applications

Used locally as building or landscaping stone and occasionally as a carving or lapidary material; ordinary pieces have little jewelry value.

Geological facts

“Greenstone” is a broad field term rather than one precise mineral or rock. Similar-looking specimens include serpentinite, greenschist, altered granite, and jade-like rocks.

Field identification & locations

Look for a dense green color, mottling, fine grain, and possible white veins; a streak, hardness, magnetism, specific gravity, and thin-section test would improve identification. Common in metamorphic belts and altered volcanic terrains.