metamorphic
Quartz-rich metamorphic rock, likely garnet-mica schist or gneiss
Quartz–feldspar–mica metamorphic rock; probable biotite schist/gneiss
AI-generated identification · may be incorrectCoarse-grained, pale gray to white quartz and feldspar with dark biotite/amphibole-rich bands and rusty iron-oxide staining. Quartz has Mohs hardness 7 and vitreous luster; the specimen shows foliation, uneven fracture, and likely specific gravity around 2.6–2.8.
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Physical properties
Coarse-grained, pale gray to white quartz and feldspar with dark biotite/amphibole-rich bands and rusty iron-oxide staining. Quartz has Mohs hardness 7 and vitreous luster; the specimen shows foliation, uneven fracture, and likely specific gravity around 2.6–2.8.
Formation & geological history
Formed when a clay- or feldspar-rich protolith was subjected to substantial heat and pressure during regional metamorphism, producing aligned mica and compositional banding. Its exact geological age cannot be determined from the photograph.
Uses & applications
Commonly used as decorative stone, landscape rock, aggregate, or building facing when sound; attractive pieces may be collected, though this example is not gem-grade.
Geological facts
The dark layers are likely mica or amphibole, while translucent white areas are quartz. Rusty brown zones commonly represent weathering of iron-bearing minerals.
Field identification & locations
Look for foliation, glittering mica flakes, interlocking quartz grains, and hard edges that do not scratch easily; a definitive identification requires a fresh surface, hand lens, and hardness tests. Common in regional metamorphic belts worldwide.
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