metamorphic
Polished greenstone (likely serpentinite or chlorite-rich schist)
Serpentinite/chlorite-rich ultramafic metamorphic rock; composition commonly dominated by serpentine-group minerals, chlorite, magnetite, and minor amphibole or pyroxene
AI-generated identification · may be incorrectMohs hardness typically 2.5–5.5, mottled dark green, olive, brown, and black; waxy to glassy polished luster, fine-grained massive texture, and generally indistinct cleavage. The rounded shape and high sheen indicate tumbling or polishing.
Identified More metamorphic →
Explore Polished greenstone (likely serpentinite or chlorite-rich schist) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Mohs hardness typically 2.5–5.5, mottled dark green, olive, brown, and black; waxy to glassy polished luster, fine-grained massive texture, and generally indistinct cleavage. The rounded shape and high sheen indicate tumbling or polishing.
Formation & geological history
Forms when magnesium-rich ultramafic rocks are hydrated and metamorphosed, commonly in oceanic crust and subduction-zone mélanges; ages vary from ancient Precambrian to modern tectonic settings.
Uses & applications
Used as decorative stone, carvings, cabochons, worry stones, and occasionally architectural facing; generally modest lapidary value.
Geological facts
The photograph cannot distinguish serpentinite confidently from chlorite-rich schist or altered basalt; a streak, hardness, density, and thin-section test would help.
Field identification & locations
Look for green-black mottling, very fine texture, waxy feel, and possible magnetism from magnetite. Common sources include California, New Zealand, Italy, Canada, and major ophiolite belts.
More like this
