igneous
Weathered quartz-rich rock, likely granite or granitic gneiss
Granite (quartz–feldspar–mica aggregate), possibly weathered granitic gneiss
AI-generated identification · may be incorrectLight gray, coarse crystalline texture with visible translucent quartz and pale feldspar; minor brown iron-oxide staining and mica may be present. Individual minerals are typically Mohs 6–7; nonfoliated granite has no cleavage as a whole, though feldspar cleaves, and quartz has vitreous luster.
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Physical properties
Light gray, coarse crystalline texture with visible translucent quartz and pale feldspar; minor brown iron-oxide staining and mica may be present. Individual minerals are typically Mohs 6–7; nonfoliated granite has no cleavage as a whole, though feldspar cleaves, and quartz has vitreous luster.
Formation & geological history
Formed when silica-rich magma slowly crystallized deep underground, generally during Precambrian to Phanerozoic continental crust formation; surface weathering produced the rusty staining and rounded edges.
Uses & applications
Commonly used as building stone, aggregate, paving, monuments, and countertops; attractive pieces may be used as study or landscaping specimens. This rough fragment has little commercial value.
Geological facts
The white-to-gray grains are most consistent with quartz and feldspar, while brown areas are likely limonite or other iron oxides. A definitive identification would require a fresh surface, hand lens, and tests for foliation and mineral proportions.
Field identification & locations
Common worldwide in continental regions, especially exposed shields and mountain belts. Look for interlocking grains, quartz that scratches glass, and feldspar faces; value is typically $1–$10 for an ordinary hand specimen, or $10–$30 if unusually attractive.
