metamorphic
Weathered mafic metamorphic rock, likely serpentinite or altered basalt
Probably serpentinized ultramafic rock; commonly dominated by serpentine-group minerals, with magnetite and altered pyroxene/olivine
AI-generated identification · may be incorrectDark gray-brown, fine- to medium-grained, dull to weakly waxy luster, irregular massive texture, and no obvious crystal faces or cleavage. Hardness is approximately 3–6 depending on alteration; specific gravity commonly 2.6–3.3.
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Physical properties
Dark gray-brown, fine- to medium-grained, dull to weakly waxy luster, irregular massive texture, and no obvious crystal faces or cleavage. Hardness is approximately 3–6 depending on alteration; specific gravity commonly 2.6–3.3.
Formation & geological history
Likely formed by hydration and metamorphic alteration of mantle-derived peridotite or mafic igneous rock, generally during tectonic plate convergence or ocean-floor alteration. Its exact age cannot be determined from the photograph.
Uses & applications
Serpentinite is used as decorative stone, carving material, aggregate, and occasionally architectural stone; attractive pieces may be collected, though fibrous asbestos-bearing varieties require caution.
Geological facts
Serpentinite can contain magnetite and may show a weak magnetic response. It is commonly associated with ophiolites and other ancient fragments of oceanic lithosphere.
Field identification & locations
Common in tectonic mountain belts, especially California, Italy, Greece, New Zealand, and parts of the Appalachians. A waxy feel, greenish tones, slick surfaces, and a relatively soft scratch response support serpentinite; the image alone cannot confirm the identification.
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