metamorphic
Likely serpentine pebble
Serpentinite; predominantly serpentine-group minerals, Mg₃Si₂O₅(OH)₄
AI-generated identification · may be incorrectTypically green, gray, or black with waxy to greasy luster, mottled veining, and hardness about 2.5–4 Mohs; massive rather than visibly crystalline. The curved, polished-looking surface appears consistent with water-worn serpentinite, though the image alone cannot confirm the diagnosis.
Identified More metamorphic →
Explore Likely serpentine pebble in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Typically green, gray, or black with waxy to greasy luster, mottled veining, and hardness about 2.5–4 Mohs; massive rather than visibly crystalline. The curved, polished-looking surface appears consistent with water-worn serpentinite, though the image alone cannot confirm the diagnosis.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite are hydrated during metamorphism, commonly in oceanic lithosphere and subduction-related belts. Serpentinization is mainly Paleozoic to modern in exposed terrains, with age dependent on the host rock.
Uses & applications
Used decoratively as ornamental stone, carvings, countertops, and lapidary material; some varieties are collected as polished or naturally shaped specimens. Fibrous asbestos-bearing serpentinite should not be cut or abraded without testing.
Geological facts
Its distinctive green coloration and slick, waxy feel result from hydration of magnesium-rich silicates. It may contain magnetite, chromite, talc, or veining minerals such as quartz and carbonate.
Field identification & locations
Field clues include low hardness, green-black mottling, waxy feel, and a relatively heavy, fine-grained texture; it may scratch with a steel knife but not glass. Common in California, the Appalachian Mountains, New Zealand, Italy, and ultramafic belts worldwide.
More like this
