igneous
Weathered granitic rock fragment
Likely granite or granodiorite, composed chiefly of quartz, feldspar, and mica/hornblende
AI-generated identification · may be incorrectHardness about 6–7 Mohs; mottled gray-brown with rusty weathering, granular texture, and dull to weakly vitreous luster. Interlocking crystals are visible, with no obvious cleavage at this scale; typical specific gravity is 2.6–2.8.
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Physical properties
Hardness about 6–7 Mohs; mottled gray-brown with rusty weathering, granular texture, and dull to weakly vitreous luster. Interlocking crystals are visible, with no obvious cleavage at this scale; typical specific gravity is 2.6–2.8.
Formation & geological history
Formed by slow crystallization of silica-rich magma deep in the crust, generally during Precambrian to Phanerozoic plutonic events, then exposed and rounded by weathering or transport.
Uses & applications
Common granitic material is used for crushed aggregate, building stone, countertops, and monuments; this small weathered fragment has negligible commercial value but may be a casual specimen.
Geological facts
The brown coloration likely comes from oxidation of iron-bearing minerals or staining by iron oxides. A fresh broken surface would better reveal its original gray, pink, or speckled granitic appearance.
Field identification & locations
Look for visible quartz and feldspar grains, interlocking texture, and lack of layering or vesicles; it is commonly found in upland outcrops, stream gravels, and glacial deposits. Exact identification requires a fresh surface or magnification.
