metamorphic

Serpentinite (often containing Jadeite/Nephrite)

Antigorite-rich Serpentine Rock, (Mg, Fe)3Si2O5(OH)4

AI-generated identification · may be incorrect

Hardness: 3-6 (depending on mineral mix); Color: Mottled green, dark green, and white; Luster: Greasy, waxy, or silky; Crystal structure: Monoclinic; Cleavage: Poor; Specific gravity: 2.5–2.6.

Hardness: 3-6 (depending on mineral mix)
Color: Mottled green, dark green, and white
Luster: Greasy, waxy, or silky

Identified April 8, 2026More metamorphic →

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Physical properties

Hardness: 3-6 (depending on mineral mix); Color: Mottled green, dark green, and white; Luster: Greasy, waxy, or silky; Crystal structure: Monoclinic; Cleavage: Poor; Specific gravity: 2.5–2.6.

Formation & geological history

Formed through serpentinization, a low-temperature metamorphic process involving the hydration of ultramafic rocks (like peridotite) from the Earth's mantle, typically at tectonic plate boundaries/subduction zones.

Uses & applications

Used as decorative stone, in sculpture, as a source of magnesium, and sometimes as a low-grade gemstone (often marketed as 'New Jade'). Historically used for heat-resistant materials.

Geological facts

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

Field identification & locations

Identify by its 'serpent-like' green mottled appearance and waxy feel. It is commonly found in ophiolite belts, such as those in the Coast Ranges of California, the Alps, and New Zealand.