sedimentary

Quartz Pebble

Silicon Dioxide (SiO2)

Hardness of 7 on the Mohs scale, typically white, clear, or stained with iron oxides (giving it a brownish or reddish tint), vitreous to greasy luster, hexagonal crystal system when well-formed but rounded here due to weathering, conchoidal fracture, specific gravity of 2.65.

Identified August 4, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through weathering and erosion of primary igneous, metamorphic, or older sedimentary rocks. Quartz is highly resistant to chemical and mechanical weathering, allowing it to survive long transport in rivers and streams where it becomes rounded into a pebble.

Uses & applications

Used in landscaping, decorative gravel, construction aggregate, and occasionally tumbled or cut for amateur lapidary work.

Geological facts

Quartz is one of the most abundant minerals in the Earth's continental crust. Because of its extreme durability, quartz sand and pebbles can persist through multiple cycles of rock formation and erosion.

Field identification & locations

Easily identified by its high hardness (scratches glass), lack of cleavage, and resistance to acid. Commonly found in riverbeds, beaches, and conglomeratic sedimentary rock formations worldwide.