metamorphic
Rounded gray pebble, likely quartzite or fine-grained granite
Quartzite (mostly SiO₂), tentative identification
AI-generated identification · may be incorrectHardness about 7 Mohs; gray-white, dull to weakly sparkling luster, massive granular texture, and no obvious cleavage. The rounded shape and smooth surface indicate water or abrasion wear; image details are insufficient for a definitive identification.
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Physical properties
Hardness about 7 Mohs; gray-white, dull to weakly sparkling luster, massive granular texture, and no obvious cleavage. The rounded shape and smooth surface indicate water or abrasion wear; image details are insufficient for a definitive identification.
Formation & geological history
If quartzite, it formed when quartz-rich sandstone was metamorphosed under heat and pressure, commonly during mountain-building; its exact geological age and locality cannot be determined visually. It may alternatively be a granitoid or another durable silicate pebble.
Uses & applications
Suitable as a decorative stone, landscaping pebble, aggregate, or lapidary material; typically not gem quality. Quartzite is also used for countertops, building stone, and crushed aggregate.
Geological facts
Quartzite commonly scratches glass and resists weathering, explaining its survival as a rounded pebble. A streak, hardness test, and close inspection of grain size would improve identification.
Field identification & locations
Common in stream beds, glacial deposits, beaches, and gravel pits worldwide. Look for sugary interlocking quartz grains and inability to scratch it with a steel knife; vinegar will not fizz.
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