igneous
Quartz-bearing granite or granitic gneiss cobble
Granite; primarily quartz (SiO₂), feldspar, and mica/amphibole
AI-generated identification · may be incorrectCoarse, speckled gray-brown rock with visible translucent quartz and dark mafic minerals; quartz hardness 7, feldspar about 6, overall Mohs roughly 6–7. It has a granular crystalline texture, generally no cleavage as a whole, and a typical specific gravity near 2.6–2.8.
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Physical properties
Coarse, speckled gray-brown rock with visible translucent quartz and dark mafic minerals; quartz hardness 7, feldspar about 6, overall Mohs roughly 6–7. It has a granular crystalline texture, generally no cleavage as a whole, and a typical specific gravity near 2.6–2.8.
Formation & geological history
Likely crystallized slowly from silica-rich magma deep within the continental crust, commonly during Precambrian to younger mountain-building events; weathering and stream or glacial transport rounded the specimen.
Uses & applications
Granite is widely used as building stone, dimension stone, countertops, aggregate, monuments, and landscaping material; this rounded specimen is mainly suitable for collecting or display.
Geological facts
The pale glassy grains are quartz, while lighter blocky grains are feldspar and darker flecks may be biotite or hornblende. The image cannot reliably distinguish granite from closely related granitic gneiss or weathered quartz-rich rock.
Field identification & locations
Identify it by its interlocking visible grains, abundant quartz, and hardness; it should scratch glass and resist a steel knife. Common in continental shields, mountain belts, glacial deposits, and stream gravels.
