metamorphic
Quartz-veined dark metamorphic rock, likely schist or gneiss
Quartz-bearing mica schist/gneiss; mainly quartz (SiO₂), feldspar, mica, and iron-oxide staining
AI-generated identification · may be incorrectDark gray to black, irregularly foliated, with white massive quartz veins and rusty brown oxidation; quartz has Mohs hardness 7 and vitreous luster, while mica contributes platy cleavage. Specific gravity is approximately 2.6–2.8.
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Physical properties
Dark gray to black, irregularly foliated, with white massive quartz veins and rusty brown oxidation; quartz has Mohs hardness 7 and vitreous luster, while mica contributes platy cleavage. Specific gravity is approximately 2.6–2.8.
Formation & geological history
Formed when mudstone or igneous protolith was buried, heated, and compressed during regional metamorphism, with silica-rich fluids later filling fractures as quartz veins. Exact geological age cannot be determined from the photograph.
Uses & applications
Used locally as landscaping stone, aggregate, or decorative specimen; attractive pieces may be collected, though this example appears mainly of geological interest.
Geological facts
The white material is likely milky quartz, while reddish-brown areas are iron oxides such as hematite or limonite. Dark foliation and cross-cutting quartz are characteristic of metamorphic vein systems.
Field identification & locations
Common in metamorphic mountain belts worldwide, including the Appalachians, Canadian Shield, Alps, and many Precambrian terrains. Look for foliation, mica sparkle, quartz veins, and a hard scratch-resistant white component.
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