mineral

Banded Agate (Tumbled)

Cryptocrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5–7 (Mohs scale); Color: Variegated bands of brown, black, grey, and white; Luster: Vitreous to waxy; Crystal structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific gravity: 2.58–2.64.

Hardness: 6
Color: Variegated bands of brown, black, grey, and white
Luster: Vitreous to waxy

Identified March 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed in volcanic rock cavities or ancient sedimentary layers where silica-rich groundwater deposits layers of rhythmic crystallization over thousands of years. Common in Cenozoic era basaltic flows.

Uses & applications

Used primarily in lapidary arts for jewelry, beads, and cabochons. Long history of use in making burnishing tools, mortar and pestles, and ornamental carvings.

Geological facts

Ancient Romans believed agate helped with harvests and protection. Its distinct banding is known as 'Liesegang rings,' caused by the periodic precipitation of minerals within the silica gel.

Field identification & locations

Identify by its characteristic colorful banding and translucent to opaque edges when held to light. Common in Brazil, India, and lake shores in the Northern US. Tumbled pieces are very smooth and rounded.