Serpentinite

Physical Properties

Hardness: 3-6 (Mohs scale), Color: Dark green to light green, blackish-green. Luster: Waxy, greasy, or silky. Crystal structure: Usually massive or fibrous. Cleavage: Poor; often exhibits a splintery or conchoidal fracture. Specific Gravity: 2.5-2.6.

Formation & Geological History

Formed through the hydration of ultramafic rocks (like peridotite or pyroxenite) from the Earth’s mantle during a process called serpentinization, typically occurring at tectonic plate boundaries.

Uses & Applications

Used as an ornamental building stone (Verde Antique), for carving, as a source of magnesium, and historically as a source of asbestos. Occasionally used in jewelry as low-grade jade substitutes.

Geological Facts

Serpentinite is the state rock of California. It is unique because it often supports rare flora that can tolerate the high magnesium and heavy metal concentrations found in soils derived from it.

Field Identification & Locations

Identify in the field by its distinctive 'scaly' or 'snake-skin' appearance, greasy feel, and green color. Commonly found in ophiolite complexes and subduction zones in places like California, the Alps, and New Zealand.

Identified on: 4/25/2026

Mode: Standard