Banded Agate

Physical Properties

Hardness: 6.5-7 on Mohs scale; Color: Banded layers of white, tan, and orange-pink; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.64.

Formation & Geological History

Formed in cavities (vesicles) of volcanic or sedimentary rocks through the deposition of silica from groundwater. The bands represent different stages of mineral precipitation. Most date from the Mesozoic or Cenozoic eras.

Uses & Applications

Primarily used in jewelry (cabochons), lapidary art, decorative ornaments, and specifically valued by collectors for its unique banding patterns.

Geological Facts

Agates are named after the Achates River in Sicily where they were first found. The banding reflects the rhythmic crystallisation of silica. No two agates are exactly alike in their pattern.

Field Identification & Locations

Identified by concentric banding and translucency. Commonly found in riverbeds, along beaches, and in volcanic regions. To identify in the field, look for a waxy luster on fractured surfaces and a hardness that can scratch glass.

Identified on: 5/20/2026

Mode: Standard