metamorphic

Likely greenstone (metamorphosed basalt)

Greenschist or chlorite–epidote altered basalt; commonly composed of chlorite, epidote, actinolite, albite, and quartz

AI-generated identification · may be incorrect

Hardness about 5–6.5 Mohs; gray-green, fine-grained, mottled, and dull to slightly waxy; massive texture with no obvious cleavage. The rounded shape and smooth surface indicate water-worn pebble abrasion.

Identified August 16, 2026More metamorphic →

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At a glance

Common name: Likely greenstone (metamorphosed basalt)
Scientific name: Greenschist or chlorite–epidote altered basalt; commonly composed of chlorite, epidote, actinolite, albite, and quartz
Category: metamorphic
Identified: August 16, 2026
Method: Standard

AI Estimated Value

$1–$10 as a common beach pebble; $10–$50 if unusually attractive, polished, or confirmed as a rarer 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

Formed when basaltic oceanic crust underwent low-grade regional metamorphism and hydrothermal alteration, typically during ancient tectonic activity; exact age and locality cannot be determined from the image.

Uses & applications

Used locally as landscaping stone, aggregate, and decorative carving material; attractive specimens may be polished for cabochons or display.

Geological facts

The green color generally comes from chlorite, epidote, or actinolite rather than a single mineral. “Greenstone” is a broad field term and can also refer to altered volcanic rocks or jade-like materials.

Field identification & locations

Common along beaches, rivers, and glacial deposits derived from volcanic or metamorphic bedrock. Identify by its dense fine grain, green-gray color, toughness, and lack of visible glassy or vesicular texture; laboratory testing is needed to distinguish it from serpentinite or jade.