igneous
Weathered quartz-rich rock, possibly granite or rhyolite
Granite–rhyolite-like felsic silicate aggregate; chiefly quartz and feldspar with minor mica/iron oxides
AI-generated identification · may be incorrectLight tan, fine- to medium-grained, earthy/weathered surface with visible pale grains and dark specks; likely Mohs 6–7, vitreous to dull luster, no obvious cleavage as a whole rock, and granular crystalline texture.
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Physical properties
Light tan, fine- to medium-grained, earthy/weathered surface with visible pale grains and dark specks; likely Mohs 6–7, vitreous to dull luster, no obvious cleavage as a whole rock, and granular crystalline texture.
Formation & geological history
Likely an ancient felsic igneous rock formed when silica-rich magma cooled slowly underground (granite) or rapidly at/near the surface (rhyolite), then chemically weathered; age cannot be determined from the photograph.
Uses & applications
Unweathered material may serve as aggregate, building stone, or decorative rock, but this small weathered fragment has little practical use and limited specimen value.
Geological facts
The rounded triangular shape and brown coating appear produced by erosion and oxidation rather than original crystal form; the image does not show diagnostic crystals or textures sufficient for a precise identification.
Field identification & locations
Look for hard, pale quartz grains that resist scratching, feldspar grains, and possible mica flakes; vinegar will not fizz unless carbonate is present. Common worldwide in continental crust and gravel deposits.
