igneous
Rounded granite or granitic gneiss cobble
Granite; chiefly quartz, feldspar, and mica
AI-generated identification · may be incorrectCoarse crystalline but heavily weathered, gray-brown, dull to weakly granular luster, with scattered pale quartz/feldspar flecks; Mohs hardness about 6–7, no obvious cleavage as a whole, specific gravity roughly 2.6–2.7.
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Physical properties
Coarse crystalline but heavily weathered, gray-brown, dull to weakly granular luster, with scattered pale quartz/feldspar flecks; Mohs hardness about 6–7, no obvious cleavage as a whole, specific gravity roughly 2.6–2.7.
Formation & geological history
Formed by slow cooling of silica-rich magma deep underground, commonly during Precambrian to younger continental crust formation; its rounded shape likely developed through stream or glacial transport and abrasion.
Uses & applications
Used as landscaping stone, cobbles, aggregate, and occasionally building stone; this weathered specimen has little jewelry value.
Geological facts
The smooth, oval form indicates prolonged mechanical abrasion, while the brown surface reflects weathering of iron-bearing minerals and feldspar.
Field identification & locations
Identify granite by visible interlocking quartz and feldspar grains, hardness, and lack of layering; distinguish gneiss by clear mineral banding, which is not evident here. Common in glacial deposits, streambeds, and granitic terrains worldwide.
