igneous
Weathered quartz-rich pebble
Milky quartz, SiO₂, possibly quartzite or a quartz-rich granite fragment
AI-generated identification · may be incorrectPale yellow to cream, opaque, dull to weakly waxy luster, massive granular texture, and no obvious cleavage; quartz hardness is Mohs 7, with specific gravity about 2.65. The rounded shape and surface pitting indicate substantial abrasion and weathering.
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Physical properties
Pale yellow to cream, opaque, dull to weakly waxy luster, massive granular texture, and no obvious cleavage; quartz hardness is Mohs 7, with specific gravity about 2.65. The rounded shape and surface pitting indicate substantial abrasion and weathering.
Formation & geological history
Likely eroded from a quartz vein, quartzite, or felsic igneous rock and rounded in a river, beach, or glacial deposit. Quartz commonly formed in hydrothermal veins or crystallized in igneous rocks over geologic timescales; its exact age cannot be determined from the image.
Uses & applications
Common quartz-rich pebbles are mainly decorative, landscaping, aggregate, and educational specimens; transparent varieties are used as gemstones and in electronics. This specimen appears to have little commercial value.
Geological facts
The yellow coloration may come from iron-oxide staining, clay, or weathering coatings rather than the quartz itself. Quartz typically resists erosion, allowing it to survive as a rounded pebble after softer minerals are removed.
Field identification & locations
A glass-scratch test can help confirm quartz: it should scratch ordinary glass, while a steel knife generally will not scratch it. Common sources include stream gravels, beaches, glacial tills, and quartz-vein outcrops worldwide.
