mineral

Quartz Pebble

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale), Color: tan to milky white, Luster: waxy to vitreous (when polished), Crystal Structure: trigonal (not visible in pebble form), Cleavage: none (conchoidal fracture)

Identified July 14, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale), Color: tan to milky white, Luster: waxy to vitreous (when polished), Crystal Structure: trigonal (not visible in pebble form), Cleavage: none (conchoidal fracture)

Formation & geological history

Formed from hydrothermal veins or as a constituent of igneous rocks, subsequently eroded and rounded by water transport in riverbeds or coastal environments. Likely millions of years old based on typical tectonic cycles.

Uses & applications

Commonly used as decorative landscaping stone, in aquarium gravel, and as a source for high-purity silica in glass making or industrial abrasives. Smooth pebbles are also popular for worry stones and tumbling.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Its high hardness and chemical resistance allow it to survive erosion longer than most other minerals, explaining why most beach sand and river pebbles are composed of quartz.

Field identification & locations

Identify in the field by its hardness (it will scratch glass), lack of visible grains, and the fact it will not react with acid. Frequently found in riverbeds, glacial deposits, and along coastlines worldwide.