Mineral

Quartz pebble

Silicon dioxide (SiO2)

Hardness: 7 on the Mohs scale. Color: Generally milky white to pale grey in this tumbled form. Luster: Vitreous to greasy. Crystal structure: Hexagonal (though not apparent in water-worn pebbles). Cleavage: None, exhibits conchoidal fracture.

Hardness: 7 on the Mohs scale
Color: Generally milky white to pale grey in this tumbled form
Luster: Vitreous to greasy

Identified June 4, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous, metamorphic, and sedimentary rocks. Often originates as vein fillings or in pegmatites. The smooth, rounded shape indicates it has been subjected to water transport, such as in a river or beach environment.

Uses & applications

Common quartz is used in glassmaking, abrasives, foundry sand, and the petroleum industry. Tumbled pebbles like this are often used for decorative purposes, landscaping, or as inexpensive collector stones.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. It is highly resistant to weathering, which is why it often survives to form sand and rounded pebbles in riverbeds.