metamorphic

Greenstone, likely altered basalt (possibly serpentinite)

Metabasalt/greenschist; commonly chlorite–actinolite–epidote ± serpentine

AI-generated identification · may be incorrect

Dark green-gray, fine-grained, dull to faintly silky luster, massive texture, and no obvious cleavage; approximate hardness 5–6 if metabasalt, or 3–5 if serpentinite. Identification is limited by the photograph; the pale streaks may be alteration minerals.

Identified September 2, 2026More metamorphic →

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At a glance

Common name: Greenstone, likely altered basalt (possibly serpentinite)
Scientific name: Metabasalt/greenschist; commonly chlorite–actinolite–epidote ± serpentine
Category: metamorphic
Identified: September 2, 2026
Method: Standard

AI Estimated Value

Typically $1–$15 for an unremarkable hand specimen; roughly $20–$100 if polished, unusually patterned, or confirmed as quality jade-like material.

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- to moderate-grade metamorphism during seafloor hydrothermal alteration or regional metamorphism, commonly in ancient oceanic crust and accretionary belts. Exact geological age cannot be determined visually.

Uses & applications

Used locally as landscaping stone, carving material, or aggregate; attractive pieces may be sold as decorative greenstone, though this specimen appears ordinary rather than gem quality.

Geological facts

“Greenstone” is a broad field term rather than one precise mineral or rock. Chlorite and epidote commonly produce green color in metamorphosed basalt, while serpentine gives a waxier appearance and lower hardness.

Field identification & locations

Look for a heavy, compact green rock with a fine texture; a steel nail test, streak test, and acid reaction can help distinguish it from softer serpentinite or carbonate rock. Common settings include ophiolites, greenstone belts, and metamorphic mountain belts.