igneous
Weathered granitoid pebble
Likely biotite granite or granodiorite, composed mainly of quartz, feldspar, and mica
AI-generated identification · may be incorrectCoarse crystalline texture with muted tan-pink feldspar, gray quartz, and dark mica; vitreous to dull luster, uneven fracture, and Mohs hardness about 6–7. The rounded shape reflects stream or beach abrasion and weathering.
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Physical properties
Coarse crystalline texture with muted tan-pink feldspar, gray quartz, and dark mica; vitreous to dull luster, uneven fracture, and Mohs hardness about 6–7. The rounded shape reflects stream or beach abrasion and weathering.
Formation & geological history
Formed when silica-rich magma slowly cooled underground, commonly during Precambrian to Phanerozoic continental plutonism; later exposed and rounded by erosion and transport.
Uses & applications
Used as aggregate, building stone, landscaping material, and decorative rock; this small weathered specimen has little commercial value.
Geological facts
Granite and granodiorite are among Earth’s most abundant continental rocks, and their visible grains indicate slow underground cooling rather than volcanic eruption.
Field identification & locations
Identify it by interlocking visible grains, abundant light feldspar and quartz, scattered dark mica, and lack of layering or foliation; common in continental mountain belts, glacial deposits, riverbeds, and beaches.
