metamorphic
Polished serpentine pebble
Serpentinite, chiefly serpentine-group minerals (antigorite/lizardite; approximate formula Mg3Si2O5(OH)4)
AI-generated identification · may be incorrectTypically olive-green to yellow-brown with mottled or veined patterns, waxy to greasy luster, and opaque appearance; Mohs hardness is about 2.5–4. It has a fine-grained, massive structure and no obvious cleavage. The wet, highly polished surface enhances its color.
Identified More metamorphic →
Explore Polished serpentine pebble in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Typically olive-green to yellow-brown with mottled or veined patterns, waxy to greasy luster, and opaque appearance; Mohs hardness is about 2.5–4. It has a fine-grained, massive structure and no obvious cleavage. The wet, highly polished surface enhances its color.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite undergo low-temperature hydrothermal alteration and hydration. Serpentinite is generally Paleozoic to Cenozoic, though the original mantle rocks may be much older.
Uses & applications
Used as a decorative stone, carvings, cabochons, tumbled stones, countertops, and ornamental objects; historically used as “green marble.”
Geological facts
The specimen’s rounded shape and glossy finish indicate human polishing, and its yellow-green color is consistent with serpentine, though visual identification alone is not definitive; similar stones include nephrite and soapstone.
Field identification & locations
Common in tectonic belts and ophiolites, including California, Vermont, Italy, New Zealand, and the Canadian Appalachians. A hardness or specific-gravity test and thin-section analysis can distinguish it from jade.
More like this
