sedimentary

Banded Chert / Agate Pebble

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale. Color: Tan, brown, beige, and cream in concentric/wavy bands. Luster: Waxy to dull (smooth stream-worn surface). Cleavage: None (conchoidal fracture). Specific Gravity: ~2.65.

Hardness: 6
Color: Tan, brown, beige, and cream in concentric/wavy bands
Luster: Waxy to dull (smooth stream-worn surface)

Identified July 25, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed by precipitation of microcrystalline quartz or silica-rich fluid deposition in sedimentary rocks or volcanic cavities. Weathered out and stream-tumbled into a smooth pebble over thousands to millions of years.

Uses & applications

Lapidary projects, tumbling, decorative landscaping, and amateur rockhounding collecting.

Geological facts

Banded chert and agates are extremely durable microcrystalline quartz specimens. Due to high silica content, early humans frequently used chert and chalcedony for crafting sharp tools such as arrowheads, scrapers, and blades.

Field identification & locations

Look for distinct swirling or concentric bands with a smooth, waxy feel and lack of visible mineral grains. Commonly found in riverbeds, gravel pits, beaches, and glacial till worldwide.