mineral

Quartz Pebbles and Agates

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: transparent orange to opaque white/yellow; Luster: vitreous to waxy; Crystal structure: Hexagonal/Trigonal; Cleavage: none (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: transparent orange to opaque white/yellow
Luster: vitreous to waxy

Identified July 6, 2026More mineral →

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Physical properties

Formation & geological history

Formed from silica-rich fluids precipitating in rock cavities (geodes) or as veins. The smooth shape indicates these are water-worn river stones or beach pebbles weathered over hundreds of thousands of years.

Uses & applications

Commonly used for lapidary work (tumbling), decorative landscaping, construction aggregate, and as minor gemstones (carnelian/agate).

Geological facts

The orange-colored specimens are a variety of chalcedony known as carnelian, which has been used as a gemstone since the Bronze Age for seals and jewelry. The white and tan stones are common quartz pebbles.

Field identification & locations

Look for rounded, translucent stones in riverbeds, gravel pits, or beaches. Identify by their hardness (cannot be scratched by a steel knife) and characteristic waxy luster when broken or polished.