metamorphic

Greenstone (likely serpentinite or altered basalt)

Serpentinite-group rock, commonly dominated by antigorite/lizardite; exact identification requires testing

AI-generated identification · may be incorrect

Dark bluish-green, fine-grained, massive, and dull to subtly waxy; likely Mohs 2.5–5.5 depending on mineral mix, with no visible cleavage or crystals. The rounded surface appears naturally weathered or water-worn.

Identified September 5, 2026More metamorphic →

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At a glance

Common name: Greenstone (likely serpentinite or altered basalt)
Scientific name: Serpentinite-group rock, commonly dominated by antigorite/lizardite; exact identification requires testing
Category: metamorphic
Identified: September 5, 2026
Method: Standard

AI Estimated Value

About $5–$25 as a common rough specimen; $25–$100+ if exceptionally colored, polished, locality-labeled, or suitable for carving.

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 formed by hydrothermal alteration of ultramafic rock or metamorphism of basaltic material, generally in oceanic crust and subduction-zone settings. Precise age and locality cannot be determined from the image.

Uses & applications

Used locally as decorative stone, carving material, aggregate, and occasionally ornamental “greenstone”; attractive specimens may be tumbled or polished. Serpentinite can contain chrysotile asbestos, so avoid cutting or generating dust until tested.

Geological facts

The color may come from serpentine minerals, chlorite, epidote, or actinolite; “greenstone” is a field term rather than a single rock species. Its smooth, rounded form suggests stream or beach transport.

Field identification & locations

Check streak, hardness, density, magnetism, and reaction to dilute hydrochloric acid; a scratch test and thin-section or Raman/XRD analysis are needed for confident identification. Common in ophiolites, fault zones, and metamorphic belts.