metamorphic
Tumbled green serpentine
Serpentinite; chiefly antigorite/lizardite Mg₃Si₂O₅(OH)₄
AI-generated identification · may be incorrectSmooth, rounded, pale to medium green with dark veining and waxy-to-dull luster; typically massive rather than visibly crystalline. Mohs hardness about 2.5–4, density roughly 2.5–2.6, with no obvious cleavage. The image supports serpentine, though jade or green soapstone are possible look-alikes.
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Physical properties
Smooth, rounded, pale to medium green with dark veining and waxy-to-dull luster; typically massive rather than visibly crystalline. Mohs hardness about 2.5–4, density roughly 2.5–2.6, with no obvious cleavage. The image supports serpentine, though jade or green soapstone are possible look-alikes.
Formation & geological history
Formed when ultramafic mantle rocks such as peridotite are hydrated during metamorphism, commonly in ophiolite belts and fault zones. Serpentinization is generally Mesozoic to Cenozoic in exposed California terranes, but exact age cannot be determined visually.
Uses & applications
Used as ornamental stone, carvings, beads, countertops, and lapidary material. Attractive pieces commonly sell for about $5–$30; larger, vividly patterned polished specimens may reach $50–$150.
Geological facts
California’s Coast Ranges contain abundant serpentinite, the state rock, making this identification regionally plausible near 40.2°N, 123.6°W. Some serpentine rocks contain chrysotile asbestos, so avoid cutting, drilling, or generating dust.
Field identification & locations
Check for a greasy or waxy feel, relatively low hardness, green color, and black/white veining; it may scratch with a steel knife but not glass. A hardness test, streak, and specific-gravity measurement would help distinguish it from jade, which is harder and tougher.
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