metamorphic
Serpentine (likely antigorite-rich serpentinite fragment)
Serpentine-group minerals, chiefly Mg₃Si₂O₅(OH)₄
AI-generated identification · may be incorrectTypically dark green to olive, waxy to dull luster, fine-grained and opaque; Mohs hardness about 2.5–4, with indistinct cleavage and specific gravity roughly 2.5–2.6. The rounded, mottled green appearance is consistent with a tumbled or water-worn piece.
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Physical properties
Typically dark green to olive, waxy to dull luster, fine-grained and opaque; Mohs hardness about 2.5–4, with indistinct cleavage and specific gravity roughly 2.5–2.6. The rounded, mottled green appearance is consistent with a tumbled or water-worn piece.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite hydrate during low-temperature metamorphism, commonly in oceanic crust and subduction zones. Most examples are geologically young relative to Earth’s history, though the source rocks may be ancient.
Uses & applications
Used decoratively for carvings, ornamental stone, and occasionally countertops; collectible value is usually modest. Some varieties have been marketed as jade substitutes, but serpentine is much softer than jade.
Geological facts
Serpentine is a mineral group rather than one single mineral; common species include antigorite, lizardite, and chrysotile. Chrysotile is an asbestos mineral, so avoid cutting, sanding, or creating dust from uncertain material.
Field identification & locations
Identify by its green mottling, waxy feel, low hardness, and ability to scratch with a steel knife; it should not scratch glass. Common localities include California, New Zealand, Italy, Canada, and serpentinite belts worldwide.
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