mineral

Tumbled green jasper or serpentine

Likely serpentine-group mineral, chiefly magnesium silicate; possibly epidotized or altered jasper

AI-generated identification · may be incorrect

Opaque olive-green to yellow-green, mottled, waxy-to-dull luster, fine-grained and irregularly fractured; typical hardness about Mohs 3–6 depending on composition. No visible crystal faces or cleavage; specific gravity commonly about 2.5–2.7.

Identified August 21, 2026More mineral →

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Physical properties

Formation & geological history

Most consistent with altered ultramafic rock or green jasper, formed by hydrothermal alteration and silica replacement. Serpentine is common in California’s Coast Ranges, including the broad region near 40.2°N, 123.6°W; age varies, commonly Jurassic–Cretaceous for the parent rocks.

Uses & applications

Used as a lapidary stone, tumbled specimen, carving material, and occasionally ornamental tile. Usually modest commercial value unless unusually patterned or translucent.

Geological facts

The blue-green veins and mottled appearance are characteristic of serpentinization or secondary mineral veining. California’s state rock is serpentine, although this specimen is not necessarily gem-quality serpentine.

Field identification & locations

Field identification favors serpentine if it feels relatively soft and waxy and can be scratched by a steel knife; jasper is harder and generally scratches glass. The photograph cannot reliably distinguish them, so a hardness test, streak, and specific-gravity measurement are recommended.