
sedimentary
Weathered river pebble, likely quartz-rich sandstone or iron-stained quartzite
Provisional identification: quartz-rich sandstone/quartzite; exact composition cannot be confirmed from the image
AI-generated identification · may be incorrectRounded, tan-brown, dull to weakly earthy luster with granular texture and possible iron-oxide staining; apparent hardness about 6–7 if quartz-rich, with no visible cleavage. Specific gravity is roughly 2.5–2.7.
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Physical properties
Rounded, tan-brown, dull to weakly earthy luster with granular texture and possible iron-oxide staining; apparent hardness about 6–7 if quartz-rich, with no visible cleavage. Specific gravity is roughly 2.5–2.7.
Formation & geological history
Likely natural abrasion in a stream, beach, or glacial deposit; sandstone formed from compacted sand, while quartzite formed when sandstone was metamorphosed. Age is indeterminate from a photograph.
Uses & applications
Primarily a common landscape or teaching specimen; it has little industrial or jewelry value unless confirmed as an attractive jasper, quartzite, or another distinctive rock.
Geological facts
The rounded shape records prolonged transport or weathering. Brown coloration commonly comes from limonite or hematite coating or cement.
Field identification & locations
Check for visible quartz grains, a gritty versus fused texture, and streak: quartz-rich material should not be scratched by a steel knife easily, while calcite-rich rock fizzes in dilute acid. Common in river gravels worldwide.
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