metamorphic
Greenstone, likely serpentinite
Serpentinite; predominantly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), possibly with chlorite, talc, magnetite, or antigorite
AI-generated identification · may be incorrectGray-green to olive, dull-to-waxy luster, fine-grained and massive with slick or subtly fibrous surfaces; Mohs hardness typically 2.5–4, with poor cleavage and specific gravity about 2.5–2.6. The image is consistent with serpentinite, though chlorite-rich metamorphic greenstone is another possibility.
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Physical properties
Gray-green to olive, dull-to-waxy luster, fine-grained and massive with slick or subtly fibrous surfaces; Mohs hardness typically 2.5–4, with poor cleavage and specific gravity about 2.5–2.6. The image is consistent with serpentinite, though chlorite-rich metamorphic greenstone is another possibility.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite undergo hydration and metamorphism, commonly along tectonic plate boundaries and fault zones. It can form from Paleozoic to modern settings; age cannot be determined from appearance alone.
Uses & applications
Used as decorative stone, carvings, beads, and historically as a low-grade building stone; attractive pieces may be sold as “serpentine jade,” though true jade is different.
Geological facts
Serpentinite commonly contains magnetite and may weakly attract a magnet; some varieties contain asbestos-form serpentine minerals, so avoid cutting or generating dust.
Field identification & locations
Common in ophiolites and subduction-related belts, including California, Italy, New Zealand, and the Appalachians. A greasy feel, green color, low hardness, and possible magnetism help distinguish it from jade; acid testing is generally unhelpful.
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