mineral

Banded Agate

Silicon Dioxide (SiO2) - Variety Agate

Hardness: 6.5-7 (Mohs); Color: White, grey, and brown; Luster: Vitreous to waxy; Crystal structure: Hexagonal (cryptocrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.64

Hardness: 6
Color: White, grey, and brown
Luster: Vitreous to waxy

Identified July 18, 2026More mineral →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: White, grey, and brown; Luster: Vitreous to waxy; Crystal structure: Hexagonal (cryptocrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.64

Formation & geological history

Formed in cavities within volcanic or metamorphic rocks through the rhythmic precipitation of silica from groundwater over long periods, often associated with ancient lava flows.

Uses & applications

Commonly used in jewelry, ornamental carvings, lapidary arts, and as a collector's specimen. Historically used for making precise mechanical parts like mortars and pestles.

Geological facts

Agate is named after the Achates River in Sicily where it was first discovered. The banding pattern reflects the changing chemistry of the fluids that deposited the silica layers.

Field identification & locations

Identify in the field by its characteristic concentric or wavy banding, translucent nature when back-lit, and extreme hardness. Often found in gravel beds or weathered basalt flows.