metamorphic
Greenstone (likely altered basalt or serpentinite)
Chlorite–epidote amphibolite/greenschist or serpentinite; exact identification requires testing
AI-generated identification · may be incorrectSmall, irregular, olive-green to brown specimen with dull to slightly waxy luster and probable fine-grained texture. Estimated Mohs hardness 3–6 depending on composition; no obvious cleavage or visible crystals.
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Physical properties
Small, irregular, olive-green to brown specimen with dull to slightly waxy luster and probable fine-grained texture. Estimated Mohs hardness 3–6 depending on composition; no obvious cleavage or visible crystals.
Formation & geological history
Likely formed by low- to medium-grade metamorphism or hydrothermal alteration of mafic volcanic rock, possibly during Precambrian to Phanerozoic tectonic activity. Serpentinite, if confirmed, formed by hydration of peridotite in oceanic or subduction-zone settings.
Uses & applications
Greenstone is used decoratively, as lapidary material, and occasionally for carvings or landscaping; serpentinite is also used as ornamental stone. This small rough piece has minimal commercial value.
Geological facts
The term “greenstone” is descriptive rather than a single mineral or rock species. Green color commonly comes from chlorite, epidote, actinolite, or serpentine minerals.
Field identification & locations
Common in metamorphic belts and former oceanic crust; notable sources include the Alps, Appalachians, New Zealand, California, and many Precambrian shields. Check streak, hardness, magnetism, acid reaction, and fibrous texture; a laboratory or thin-section test is needed for confident identification.
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