Serpentinite

Physical Properties

Hardness: 3-6 (Mohs scale), Color: Varying shades of green to greyish-green, Luster: Waxy, greasy, or silky, Crystal Structure: Monoclinic (mostly massive), Specific Gravity: 2.5-3.2. Often has a 'soapy' or 'slick' feel.

Formation & Geological History

Formed through the hydration and metamorphic transformation of ultramafic rocks (like peridotite) from the Earth's mantle, typically at subduction zones or mid-ocean ridges.

Uses & Applications

Used as a decorative architectural stone, source of asbestos (historically), carving material for ornaments and jewelry, and for carbon sequestration research.

Geological Facts

Serpentinite is the official state rock of California. It can produce high-magnesium soils that are toxic to many plants but host rare 'serpentine endemic' flora.

Field Identification & Locations

Look for a distinctive green color, a polished or 'slickensided' surface, and a soapy texture. It is commonly found in mountain belts where oceanic crust has been pushed onto land.

Identified on: 4/26/2026

Mode: Standard