metamorphic
Tumbled green stone, likely serpentine
Serpentinite; principally serpentine-group minerals, Mg₃Si₂O₅(OH)₄
AI-generated identification · may be incorrectDark green, mottled, and waxy-to-subvitreous with rounded tumbled surfaces; Mohs hardness about 2.5–4, poor cleavage, and specific gravity roughly 2.5–2.6. The image is insufficient for a certain identification; nephrite, chlorite, or green jasper are alternatives.
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Physical properties
Dark green, mottled, and waxy-to-subvitreous with rounded tumbled surfaces; Mohs hardness about 2.5–4, poor cleavage, and specific gravity roughly 2.5–2.6. The image is insufficient for a certain identification; nephrite, chlorite, or green jasper are alternatives.
Formation & geological history
Serpentine forms when ultramafic mantle rocks, especially peridotite, hydrate during hydrothermal alteration, commonly in oceanic crust and tectonic mélange zones. Most specimens are geologically ancient, though their exact age cannot be determined visually.
Uses & applications
Used as an ornamental and carving stone, countertop or architectural material, and inexpensive lapidary rough; quality translucent green varieties may be fashioned into beads or cabochons.
Geological facts
Serpentinite is often associated with chromite, magnetite, and asbestos-forming minerals. A streak, hardness, translucency, and specific-gravity test would improve identification; do not saw unknown serpentine because some varieties contain asbestos.
Field identification & locations
Common localities include California, Vermont, Italy, New Zealand, Canada, and the Ural Mountains. Typical tumbled pieces sell for about $2–$15; unusual color, translucency, or provenance can raise value to $25–$100.
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