Serpentine

Physical Properties

Hardness: 3-6 on Mohs scale; Color: Yellowish-green to dark green, often mottled; Luster: Greasy, waxy, or silky; Crystal structure: Monoclinic; Cleavage: Poor; Specific gravity: 2.5-2.6

Formation & Geological History

Formed through serpentinization, an exothermic metamorphic process where ultramafic rocks (like peridotite) from the Earth's mantle are altered by low-temperature hydrothermal fluids.

Uses & Applications

Commonly used for decorative carvings, architecture (green marble), jewelry-grade 'Williamsite', and was historically a source of asbestos.

Geological Facts

Serpentine is the official state rock of California. It often contains inclusions of chromite or magnetite, which can make some specimens slightly magnetic.

Field Identification & Locations

Identify in the field by its distinctive 'snake-skin' appearance, greasy feel to the touch, and greenish hue. It is often found in ophiolite complexes near tectonic plate boundaries.

Identified on: 4/28/2026

Mode: Standard