metamorphic

Serpentine-rich metamorphic rock

Serpentinite, likely with quartz or calcite veining and minor magnetite

AI-generated identification · may be incorrect

Typically dark green to black, mottled, waxy to greasy luster, with pale vein material and granular crystals; hardness is about 2.5–5.5 depending on minerals, and specific gravity is roughly 2.5–2.7. The specimen appears irregular and massive rather than showing a distinct crystal structure or cleavage.

Identified September 1, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when ultramafic mantle rocks such as peridotite are hydrated and altered during metamorphism, commonly along tectonic plate boundaries and oceanic crust. Serpentinization ranges from Paleozoic to modern geological ages.

Uses & applications

Used as decorative stone, carvings, countertops, and historical building material; attractive polished pieces are collected, though fibrous asbestos-bearing varieties require caution.

Geological facts

Its green coloration comes chiefly from serpentine minerals (antigorite, lizardite, or chrysotile). The pale patches may be calcite or quartz, while reflective dark grains may be magnetite or chromite.

Field identification & locations

Identify by green-black mottling, greasy/waxy surface, relatively low hardness, and association with white veins; a hardness and acid test can distinguish calcite from quartz. Common in California, Italy, New Zealand, Canada, and ophiolite belts worldwide.