igneous
Likely weathered granite or granitic gneiss
Granite; quartz–feldspar–mica aggregate (possibly foliated gneiss)
AI-generated identification · may be incorrectCoarse, light-gray to brown rock with visible translucent/gray quartz, pale feldspar, and dark mica or biotite; uneven granular texture, dull to glassy luster, no obvious cleavage as a whole. Typical hardness is about 6–7 Mohs and specific gravity 2.6–2.8.
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Physical properties
Coarse, light-gray to brown rock with visible translucent/gray quartz, pale feldspar, and dark mica or biotite; uneven granular texture, dull to glassy luster, no obvious cleavage as a whole. Typical hardness is about 6–7 Mohs and specific gravity 2.6–2.8.
Formation & geological history
Granite crystallizes slowly from silica-rich magma deep in continental crust, commonly during Precambrian to younger intrusive events; surface weathering rounds and roughens exposed pieces. If gneissic, it formed by high-grade metamorphism of granitic rock.
Uses & applications
Granite is widely used for dimension stone, countertops, monuments, aggregate, and architectural surfaces; attractive specimens have modest collecting value.
Geological facts
The image shows a rounded, weathered specimen rather than a diagnostic fresh surface, so exact identification is uncertain from appearance alone. Quartz and feldspar grains are the key visible components.
Field identification & locations
Look for interlocking crystals: glassy gray quartz, blocky white or pink feldspar, and black mica; it should scratch glass but not be scratched by a steel knife. Common worldwide, especially continental shield and mountain regions.
