igneous
Weathered quartz-rich pebble, likely granite or granitic gneiss
Granite/granitic gneiss; chiefly quartz (SiO₂), feldspar, and minor mica or iron oxides
AI-generated identification · may be incorrectHardness about 6–7 Mohs; rounded, pale gray to cream with brown staining, granular texture, and dull to weakly glassy luster. Interlocking quartz and feldspar grains are visible, though the image is insufficient to distinguish granite from gneiss confidently.
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Physical properties
Hardness about 6–7 Mohs; rounded, pale gray to cream with brown staining, granular texture, and dull to weakly glassy luster. Interlocking quartz and feldspar grains are visible, though the image is insufficient to distinguish granite from gneiss confidently.
Formation & geological history
Formed from slowly cooled felsic magma (granite) or metamorphosed granite (gneiss), generally in Precambrian to Phanerozoic continental crust; later rounded by stream or beach transport and weathering.
Uses & applications
Commonly used as crushed aggregate, dimension stone, landscaping gravel, and occasionally polished decorative stone; this small weathered specimen has mainly educational or modest collecting value.
Geological facts
Quartz-rich granitic rocks commonly develop rusty brown coatings from oxidation of iron-bearing minerals. The rounded shape indicates abrasion during transport rather than original crystal form.
Field identification & locations
Look for visible quartz and feldspar grains, lack of layering, and hardness sufficient to scratch glass; a streak, acid, and close inspection are needed for a firmer identification. Common worldwide in continental shields, mountain belts, riverbeds, and beaches.
