metamorphic

Chlorite-rich schist (probable greenschist)

Greenschist-facies metabasalt or chlorite–actinolite schist

AI-generated identification · may be incorrect

Fine- to medium-grained, dark gray-green rock with pale reflective mineral flakes and weak foliation; likely hardness 3–6, vitreous to pearly luster, with cleavage in mica/chlorite and amphibole. Probable minerals are chlorite, actinolite, epidote, albite, quartz, and minor opaque minerals.

Identified September 13, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when basaltic or volcanic protolith was regionally metamorphosed under low- to moderate-temperature, low- to moderate-pressure greenschist-facies conditions, commonly during mountain building. Exact age cannot be determined from the photograph.

Uses & applications

Used locally as decorative stone, aggregate, or landscaping material; attractive polished pieces may be collected, but it is generally not a gemstone or high-value building stone.

Geological facts

The green color commonly reflects chlorite and actinolite, while the pale grains may be epidote or feldspar. A hand specimen alone cannot reliably distinguish schist from altered basalt or amphibolite.

Field identification & locations

Look for planar foliation, a green-gray color, sparkly platy grains, and a relatively dense, tough texture; a streak, hardness, acid, and thin-section test would improve identification. Common in metamorphic belts worldwide, including the Alps, Appalachians, and Pacific Northwest.