metamorphic
Quartz-veined metamorphic rock, likely greenschist or altered basalt
Chlorite–actinolite schist or metabasalt with a milky quartz vein
AI-generated identification · may be incorrectDark green-gray, fine-grained, and weakly foliated with a contrasting white, massive quartz vein. Quartz has Mohs hardness 7, vitreous luster, no cleavage, and specific gravity about 2.65; the host is typically about Mohs 5–6 and may contain chlorite, actinolite, epidote, albite, and magnetite.
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Physical properties
Dark green-gray, fine-grained, and weakly foliated with a contrasting white, massive quartz vein. Quartz has Mohs hardness 7, vitreous luster, no cleavage, and specific gravity about 2.65; the host is typically about Mohs 5–6 and may contain chlorite, actinolite, epidote, albite, and magnetite.
Formation & geological history
Likely basaltic oceanic crust metamorphosed under greenschist-facies conditions, then fractured and infiltrated by silica-rich hydrothermal fluids that deposited quartz. Such rocks commonly formed during Paleozoic or younger tectonic events, though age cannot be determined from the image.
Uses & applications
Commonly collected as an attractive field specimen or used decoratively when polished; it has little commercial value unless exceptionally patterned or from a documented locality.
Geological facts
The white band is probably quartz rather than calcite because it appears hard, massive, and non-cleaved, though acid testing can help distinguish them.
Field identification & locations
Identify it by its dense green-gray host, possible faint foliation, and sharply contrasting white vein; inspect a fresh surface for green amphibole/chlorite and test the vein with a steel file and dilute acid. Comparable material occurs in metamorphic belts and altered volcanic terranes worldwide.
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