metamorphic

Greenstone (likely serpentinite or altered basalt)

Serpentinite, chiefly serpentine-group minerals; possibly chlorite- or actinolite-bearing greenschist

AI-generated identification · may be incorrect

Dark olive-green, fine-grained, opaque to slightly translucent, with a dull to waxy luster and indistinct cleavage; estimated Mohs hardness 3–5. The irregular pale veining and mottled texture are typical of serpentinization or low-grade metamorphism.

Identified September 17, 2026More metamorphic →

Explore Greenstone (likely serpentinite or altered basalt) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

At a glance

Common name: Greenstone (likely serpentinite or altered basalt)
Scientific name: Serpentinite, chiefly serpentine-group minerals; possibly chlorite- or actinolite-bearing greenschist
Category: metamorphic
Identified: September 17, 2026
Method: Standard

AI Estimated Value

About $5–$30 as a common rough specimen; $30–$150 or more if unusually attractive, polished, or provenance-documented.

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

Most likely formed by hydrothermal alteration of ultramafic rock, or metamorphism of basalt, during ancient oceanic crust and subduction-related processes; the specimen’s exact age cannot be determined from the image.

Uses & applications

Used as decorative stone, carving material, landscaping aggregate, and historically as a source rock for asbestos-bearing minerals; attractive polished pieces may be sold as ornamental stone.

Geological facts

“Greenstone” is a broad field term rather than a single mineral or rock. Serpentinite commonly contains magnetite and may show weak magnetic response; avoid cutting or sanding unknown material because some varieties contain fibrous asbestos minerals.

Field identification & locations

Common in ophiolites and metamorphic belts worldwide, including California, New England, Italy, New Zealand, and the Alps. A waxy feel, low hardness, green color, and pale veining support serpentinite, but laboratory testing is needed for a definitive identification.