metamorphic
Greenstone with quartz veins
Chlorite- and epidote-bearing metabasalt (greenstone), cut by quartz veins
AI-generated identification · may be incorrectGreen to gray-green, mottled, with pale, irregular quartz veins; typically fine-grained and dull to slightly waxy. Approximate hardness 5–7 (veins are harder); exact mineral composition and properties require testing.
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Physical properties
Green to gray-green, mottled, with pale, irregular quartz veins; typically fine-grained and dull to slightly waxy. Approximate hardness 5–7 (veins are harder); exact mineral composition and properties require testing.
Formation & geological history
Formed when basalt was altered by low-grade metamorphism and hydrothermal fluids, which produced green minerals and deposited quartz in fractures. The specimen’s age and locality cannot be determined from the photograph.
Uses & applications
Common greenstone is used as decorative or landscaping stone and occasionally for carvings or jewelry; this rough specimen’s value is mainly as a geological curiosity.
Geological facts
Greenstone is a field term for metamorphosed mafic rock colored by minerals such as chlorite, actinolite, and epidote; the visible white veins are likely quartz.
Field identification & locations
Its green color and light veins suggest greenstone, but similar appearances occur in other altered rocks; confirm with hardness, texture, and mineral tests. Greenstones occur in ancient metamorphic belts worldwide.
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