metamorphic
Quartz-veined dark metamorphic rock
Likely quartz-mica schist or foliated basalt with a quartz vein
AI-generated identification · may be incorrectDark gray, fine-grained host with a contrasting white, glassy-to-granular quartz vein; quartz hardness 7, host approximately 5–6, with nonmetallic luster and no obvious cleavage visible. The irregular white band likely consists mainly of massive quartz.
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Physical properties
Dark gray, fine-grained host with a contrasting white, glassy-to-granular quartz vein; quartz hardness 7, host approximately 5–6, with nonmetallic luster and no obvious cleavage visible. The irregular white band likely consists mainly of massive quartz.
Formation & geological history
Probably formed when silica-rich fluids filled a fracture in a pre-existing metamorphic or volcanic rock; vein formation may range from Paleozoic to younger, depending on locality. Exact identification and age require thin-section or chemical analysis.
Uses & applications
Primarily a collecting specimen; similar quartz-veined rocks are used decoratively or as aggregate, but this small piece has no significant commercial value.
Geological facts
The white material should scratch glass if it is quartz, while the dark host may be softer. A streak test and close inspection for foliation would help distinguish schist from basalt.
Field identification & locations
Common in metamorphic belts and hydrothermal vein systems worldwide, including the Appalachians, western North America, and many volcanic terrains. Look for translucent edges, quartz fracture, and mica flakes in the host.
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