mineral

Quartz Pebble (Beach Agate / Chalcedony Pebble)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Mohs hardness of 7, translucent to semi-transparent milky or clear appearance, vitreous to waxy luster, conchoidal fracture pattern, hexagonal crystal structure (microcrystalline in chalcedony), specific gravity around 2.65.

Identified July 26, 2026More mineral →

Explore Quartz Pebble (Beach Agate / Chalcedony Pebble) in the encyclopedia →

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Physical properties

Formation & geological history

Formed through precipitation of silica-rich fluids in cavities of igneous or sedimentary rocks, followed by erosion, stream transport, and natural tumbling by ocean or river waves over thousands of years.

Uses & applications

Used in lapidary work, jewelry making, tumbled stone collections, landscape decoration, and historically in glassmaking or abrasives.

Geological facts

Smooth beach pebbles like this undergo millions of natural impacts against sand and other stones in surf zones, which frost the surface and round the sharp edges.

Field identification & locations

Identified by its high hardness (scratches glass, steel cannot scratch it), smooth water-worn texture, conchoidal fracture marks, and translucent nature when held against light. Commonly found on gravel beaches, riverbeds, and glacial deposits worldwide.