metamorphic
Weathered greenstone (metamorphosed mafic rock)
Chlorite- and epidote-bearing metabasalt; exact identification requires examination
AI-generated identification · may be incorrectRough, mottled green, cream, and gray surface with a dull to slightly crystalline luster. Likely dominated by plagioclase and chlorite/epidote; hardness and crystal structure cannot be reliably determined from the image.
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Physical properties
Rough, mottled green, cream, and gray surface with a dull to slightly crystalline luster. Likely dominated by plagioclase and chlorite/epidote; hardness and crystal structure cannot be reliably determined from the image.
Formation & geological history
Forms when basalt or related mafic rock is altered by low-grade metamorphism and fluids. The specimen’s age and precise formation environment cannot be determined from appearance alone.
Uses & applications
Greenstone is used as crushed aggregate and occasionally for landscaping or decorative stone; this small irregular specimen has little apparent commercial value.
Geological facts
The green color commonly comes from chlorite, epidote, or actinolite formed during alteration of mafic minerals.
Field identification & locations
Look for a dense, fine-grained rock with green alteration minerals and possible pale veins; compare with nearby source rocks, since surface weathering can obscure identification. Greenstones occur in ancient volcanic belts worldwide.
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