mineral

Quartz pebble (Agate / Chalcedony)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: Grayish-tan to translucent brownish; Luster: Waxy to vitreous; Crystal Structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Grayish-tan to translucent brownish
Luster: Waxy to vitreous

Identified July 27, 2026More mineral →

Explore Quartz pebble (Agate / Chalcedony) in the encyclopedia →

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Physical properties

Formation & geological history

Formed through the deposition of silica from water in cavities within igneous or sedimentary rocks, then weathered and water-worn into a smooth river pebble.

Uses & applications

Commonly used in lapidary work, decorative rock collections, tumbling, and landscape ornamentation.

Geological facts

Cryptocrystalline quartz varieties like agate and chalcedony are composed of submicroscopic crystals, making them tough and highly resistant to physical weathering.

Field identification & locations

Identified by its translucency, hardness (scratches glass easily), waxy luster, and smooth, water-rounded shape. Very common in riverbeds, beach gravels, and glacial deposits worldwide.