igneous
Weathered granite or granitic gneiss cobble
Granite; mainly quartz, feldspar, and mica (exact identification is limited by the photograph)
AI-generated identification · may be incorrectLight gray-green, fine- to medium-grained, dull weathered surface with faint quartz/feldspar mottling; typical hardness is about 6–7 Mohs, no obvious cleavage as a whole rock, and specific gravity near 2.6–2.7.
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Physical properties
Light gray-green, fine- to medium-grained, dull weathered surface with faint quartz/feldspar mottling; typical hardness is about 6–7 Mohs, no obvious cleavage as a whole rock, and specific gravity near 2.6–2.7.
Formation & geological history
Likely crystallized slowly from silica-rich magma deep in the crust, commonly during Precambrian to Mesozoic continental mountain-building; later exposed and rounded by weathering, transport, or glacial action.
Uses & applications
Granite is widely used for construction aggregate, monuments, curbs, countertops, and dimension stone; this small weathered cobble has mainly modest collecting value.
Geological facts
The pale minerals are probably feldspar and quartz, while darker specks may be biotite or amphibole. A granular texture and lack of layering distinguish granite from most sedimentary rocks.
Field identification & locations
Look for interlocking visible grains, abundant pale feldspar, glassy quartz, and occasional dark mica; a streak test is unhelpful, while a steel file generally does not scratch quartz-rich grains. Common worldwide, especially in continental mountain belts and glacial deposits.
