metamorphic
Weathered quartz-bearing rock, possibly serpentine or altered ultramafic rock
Provisional identification: serpentinite or chlorite–quartz schist; exact composition requires testing
AI-generated identification · may be incorrectPale gray-green and yellow-brown, dull to weakly waxy luster, fine-grained and massive with no obvious crystal faces; likely Mohs hardness about 3–6 depending on talc, chlorite, quartz, and iron oxides. The yellow-brown areas appear weathering or iron staining.
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Physical properties
Pale gray-green and yellow-brown, dull to weakly waxy luster, fine-grained and massive with no obvious crystal faces; likely Mohs hardness about 3–6 depending on talc, chlorite, quartz, and iron oxides. The yellow-brown areas appear weathering or iron staining.
Formation & geological history
Likely formed by hydrothermal metamorphism of magnesium-rich mantle rock, with later oxidation and surface weathering; age cannot be determined from the photograph. Common in ophiolite belts and fault zones.
Uses & applications
Serpentinite is used as decorative stone, aggregate, and carving material; attractive pieces may be collected, though this specimen appears small and ordinary.
Geological facts
Serpentinite commonly contains serpentine minerals such as antigorite, lizardite, or chrysotile, sometimes with magnetite. Some varieties may contain trace asbestos-form minerals, so avoid cutting, grinding, or generating dust.
Field identification & locations
Possible identification clues include a green color, waxy feel, relatively low hardness, dark streak, and occasional magnetism; quartz-rich material will scratch glass, while talc-rich material will not. Common locations include California, the Appalachians, the Alps, and other ophiolite regions.
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