igneous
Weathered quartz-rich pebble
Likely quartzite or quartz-rich granite/granitoid; exact identification requires testing
AI-generated identification · may be incorrectHardness likely Mohs 6.5–7; rounded, fine- to medium-grained, tan/cream with pink-brown iron-oxide staining, dull to weakly vitreous luster, and no obvious cleavage. Quartz is the dominant visible mineral, with possible feldspar and minor mica or iron oxides.
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Physical properties
Hardness likely Mohs 6.5–7; rounded, fine- to medium-grained, tan/cream with pink-brown iron-oxide staining, dull to weakly vitreous luster, and no obvious cleavage. Quartz is the dominant visible mineral, with possible feldspar and minor mica or iron oxides.
Formation & geological history
Probably a glacially or stream-rounded cobble derived from weathering of quartzite or felsic igneous rock; its precise geological age and source cannot be determined from the photograph.
Uses & applications
Primarily a natural specimen, landscaping stone, or craft/tumbled stone; quartzite can be used as aggregate, building stone, and occasionally countertops, but this piece has little commercial value.
Geological facts
The smooth shape reflects abrasion during transport, while reddish-brown coloration commonly results from oxidation of iron-bearing minerals or groundwater staining.
Field identification & locations
Look for scratch resistance against glass, abundant glassy quartz grains, and absence of strong layering; a streak, acid, hardness, and thin-section test would distinguish quartzite from granite and other quartz-rich rocks. Such pebbles are common in stream gravels and glacial deposits.
