metamorphic

Serpentinite

Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)3Si2O5(OH)4

AI-generated identification · may be incorrect

Hardness: 2.5-5; Color: Dark green to black with mottled patches; Luster: Waxy, greasy, or silky; Crystal Structure: Monoclinic; Cleavage: Poor; Specific Gravity: 2.5-2.6.

Hardness: 2
Color: Dark green to black with mottled patches
Luster: Waxy, greasy, or silky

Identified June 8, 2026More metamorphic →

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Physical properties

Hardness: 2.5-5; Color: Dark green to black with mottled patches; Luster: Waxy, greasy, 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 hydrated by low-temperature water at tectonic plate boundaries.

Uses & applications

Used as decorative architectural stone, a source of magnesium, and historically as a source of asbestos. High-quality varieties are carved into figurines or jewelry.

Geological facts

Serpentinite is the official state rock of California. It often creates unique, nutrient-poor soils that support rare, endemic plant species that have evolved to tolerate high levels of heavy metals.

Field identification & locations

Identify in the field by its characteristic 'snake-skin' appearance, waxy texture, and dark green color. Often found in ophiolite complexes and subduction zones where oceanic crust meets continental crust.