mineral

Quartz River Pebble

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale), Color: tan to creamy white, Luster: vitreous to waxy, Crystal structure: trigonal (microcrystalline in this form), Cleavage: none, Specific gravity: 2.65

Identified June 19, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale), Color: tan to creamy white, Luster: vitreous to waxy, Crystal structure: trigonal (microcrystalline in this form), Cleavage: none, Specific gravity: 2.65

Formation & geological history

Formed through the cooling of silica-rich magma or precipitation from hydrothermal veins. This specific specimen has been smoothed and rounded by river action or water erosion over a long period.

Uses & applications

Commonly used in landscaping, road construction, as an abrasive, and occasionally for lapidary work or tumbled stones for hobbyists.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Its smooth surface in river rocks is a result of millions of collisions with other rocks during transport downstream.

Field identification & locations

Identify in the field by its hardness (will scratch glass), lack of bubbles when exposed to acid, and smooth, rounded water-worn texture. Commonly found in riverbeds, beaches, and glacial deposits.