mineral

Quartz-rich river pebble, likely milky quartz

Milky quartz (SiO₂), possibly a quartzite or quartz-rich silicate pebble

AI-generated identification · may be incorrect

White to cream, opaque, dull-to-waxy luster, smooth water-worn surface, and no obvious cleavage; quartz hardness is Mohs 7, with specific gravity about 2.65. The rounded shape indicates transport and abrasion, while surface staining may account for the tan patches.

Identified August 11, 2026More mineral →

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Physical properties

Formation & geological history

Most likely weathered from quartz veins or quartz-rich metamorphic rocks, then rounded in a stream or river. Quartz is commonly Precambrian to younger, but the pebble’s exact age cannot be determined visually.

Uses & applications

Common pieces have little commercial value; quartz is used in glass, ceramics, abrasives, electronics, and engineered stone. Attractive polished examples may be used decoratively.

Geological facts

Quartz commonly breaks with curved, conchoidal fracture rather than cleavage. The reported location near 17.2°N, 89.1°W is consistent with stream gravels containing quartz derived from regional sedimentary and metamorphic terrains.

Field identification & locations

Likely identification can be tested by scratching glass (quartz should scratch it), while a steel knife should not scratch it. A streak test should be white; acid reaction would suggest carbonate instead, so fizzing would indicate a different rock such as limestone.