mineral

Quartz Pebble

Silicon Dioxide (SiO2)

Mohs hardness of 7, vitreous to waxy luster, trigonal crystal system in unrounded forms, conchoidal fracture, variable color from brownish-gray to translucent quartz, specific gravity around 2.65.

Identified July 26, 2026More mineral →

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Physical properties

Mohs hardness of 7, vitreous to waxy luster, trigonal crystal system in unrounded forms, conchoidal fracture, variable color from brownish-gray to translucent quartz, specific gravity around 2.65.

Formation & geological history

Formed in hydrothermal veins, pegmatites, and as a major constituent of igneous and metamorphic rocks; later eroded and naturally rounded by water transport in rivers or ocean shores.

Uses & applications

Used commonly in landscaping, river rock aggregate, glassmaking raw material, and lapidary polishing for hobbyists.

Geological facts

Quartz is one of the most abundant minerals on Earth's surface and is extremely resistant to both physical and chemical weathering, which is why rounded quartz pebbles dominate riverbeds and gravel deposits.

Field identification & locations

Identified by its scratch resistance (scratches glass easily), smooth river-worn surface, translucency when held to light, and absence of cleavage planes. Found in gravel beds, rivers, and beaches worldwide.