igneous
Weathered granite or granitic gneiss
Felsic granitoid, chiefly quartz, feldspar, and mica; possible gneissic fabric
AI-generated identification · may be incorrectCoarse-grained, pinkish-brown and gray, with visible interlocking crystals and weathered rusty iron staining; quartz has Mohs hardness 7, feldspar 6, and mica 2–3. It has a granular texture, vitreous-to-dull luster, and no obvious cleavage as a whole rock.
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Physical properties
Coarse-grained, pinkish-brown and gray, with visible interlocking crystals and weathered rusty iron staining; quartz has Mohs hardness 7, feldspar 6, and mica 2–3. It has a granular texture, vitreous-to-dull luster, and no obvious cleavage as a whole rock.
Formation & geological history
Likely formed by slow cooling of silica-rich magma deep in the crust, potentially hundreds of millions to billions of years ago; surface weathering produced the rough, iron-stained exterior. The image is insufficient to distinguish granite confidently from metamorphosed granitic gneiss.
Uses & applications
Common granite is used as crushed aggregate, building stone, countertops, monuments, and decorative landscaping material; this small weathered piece has little commercial value.
Geological facts
Pink coloration commonly comes from potassium feldspar, while dark flecks are biotite or hornblende. Rusty red-brown patches generally indicate oxidation of iron-bearing minerals.
Field identification & locations
Look for coarse interlocking grains of pink/white feldspar, glassy gray quartz, and black mica; granite is harder and more crystalline than sandstone. Common worldwide, especially in continental mountain belts and exposed shields.
