sedimentary

Banded Agate (Tumbled)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale); Color: Translucent grey with blue/grey banding; Luster: Vitreous to waxy; Structure: Cryptocrystalline (Trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.64.

Hardness: 6
Color: Translucent grey with blue/grey banding
Luster: Vitreous to waxy

Identified July 8, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in cavities of volcanic or sedimentary rocks through the deposition of silica-rich groundwater. Associated with silica precipitation over thousands to millions of years.

Uses & applications

Jewelry, lapidary art, spiritual healing practices, industrial burnishing tools, and as a popular collector's item for beginners.

Geological facts

Agate is a variety of chalcedony. The name comes from the Achates River in Sicily where it was first discovered in ancient times. Banding is caused by rhythmic crystallization cycles.

Field identification & locations

Look for translucent surfaces with distinct internal or external concentric bands. It is commonly found in riverbeds and on beaches worldwide, particularly in Brazil and the Great Lakes region.