igneous
Rounded quartz-rich river pebble
Likely granitic or quartzitic clast; predominantly quartz (SiO₂) with feldspar and minor mica/iron oxides
AI-generated identification · may be incorrectLight tan, fine- to medium-grained, dull to weakly satin luster, rounded and weathered; likely hardness 6–7 Mohs, with no obvious cleavage and granular crystalline texture. Exact identification is limited by the photograph.
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Physical properties
Light tan, fine- to medium-grained, dull to weakly satin luster, rounded and weathered; likely hardness 6–7 Mohs, with no obvious cleavage and granular crystalline texture. Exact identification is limited by the photograph.
Formation & geological history
Most likely eroded from an older quartz-rich igneous or metamorphic rock and rounded by stream or glacial transport; its formation age could range from Precambrian to much younger depending on source locality.
Uses & applications
Primarily a natural collectible or decorative stone; quartz-rich material may be used as aggregate, landscaping stone, or occasionally lapidary material, but this specimen has little commercial value.
Geological facts
The dark streaks may be mica-rich bands, fractures, or iron/manganese staining. A steel knife should not easily scratch quartz-rich areas, while glass should be scratched by them.
Field identification & locations
Common in streambeds, gravel deposits, beaches, and glacial till worldwide. Check for visible interlocking quartz and feldspar grains, test hardness, and use a streak plate or loupe for better identification.
