sedimentary

Rounded quartz-rich pebble

Likely milky quartz or quartzite; SiO₂

AI-generated identification · may be incorrect

White to cream, fine-grained, dull to weakly vitreous luster, no obvious cleavage, hardness about 7 Mohs, and specific gravity near 2.65. Its smooth rounded shape indicates water abrasion; the image is insufficient for a definitive distinction between quartz and quartzite.

Identified September 22, 2026More sedimentary →

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Physical properties

Formation & geological history

Probably weathered from quartz-bearing igneous or metamorphic rock and transported in a stream or gravel deposit. The original quartz may be Precambrian to younger, but the pebble’s depositional age cannot be determined visually.

Uses & applications

Common material for landscaping, aggregate, drainage gravel, and lapidary tumbling; generally unsuitable as a gemstone unless unusually pure or patterned.

Geological facts

Quartz is one of Earth’s most abundant minerals and commonly survives erosion because of its high hardness and chemical durability.

Field identification & locations

Test with a steel knife or glass: true quartz should resist scratching glass and not be scratched by a knife. A streak test should be white; acid reaction is absent. Common worldwide in streambeds, glacial deposits, and conglomerates.