mineral

Banded Agate

Silicon Dioxide (SiO2) - Chalcedony variety

AI-generated identification · may be incorrect

Hardness: 6.5–7 (Mohs scale); Color: White, tan, and light brown with distinct banding; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.64.

Hardness: 6
Color: White, tan, and light brown with distinct banding
Luster: Waxy to vitreous

Identified March 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed primarily in volcanic rock cavities (vesicles) or sedimentary veins through the slow deposition of silica from groundwater. The characteristic bands are created by alternating pulses of mineral-rich fluids over thousands to millions of years.

Uses & applications

Popular in jewelry (cabochons and beads), ornamental carvings, burnishing tools for leather, and as decorative landscaping stones. Highly valued by amateur rockhounds and lapidary artists.

Geological facts

Agate was named by the Greek philosopher Theophrastus, who discovered the stone along the shore of the Achates River in Sicily. It is often found in the form of 'thundereggs' or nodules with a rough, weathered exterior hiding the colorful bands inside.

Field identification & locations

Identify in the field by its waxy texture, translucency when held to light, and visible concentric or parallel banding. Commonly found in riverbeds, beaches, and volcanic regions globally, notably in the Lake Superior region and Brazil.