Banded Agate

Physical Properties

Hardness: 6.5-7 on Mohs scale; Color: Gray, tan, white, and translucent bands; Luster: Waxy to vitreous; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.64.

Formation & Geological History

Formed as a secondary mineral in volcanic rock cavities (vesicles) where silica-rich groundwater deposits layers of microcrystalline quartz over thousands of years.

Uses & Applications

Used primarily for jewelry (cabochons), ornamental carvings, lapidary art, and as a semi-precious gemstone for collectors.

Geological Facts

Agate is named after the Achates River in Sicily. The concentric banding is actually rhythmic crystallization that creates the distinct 'ring' patterns.

Field Identification & Locations

Identify in the field by looking for translucent edges, waxy texture, and fine concentric banding. Common in volcanic regions and riverbeds.

Identified on: 5/19/2026

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