Banded Agate

Physical Properties

Hardness: 6.5-7 (Mohs scale); Color: White, grey, light blue; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Formation & Geological History

Formed primarily in volcanic and metamorphic rocks. It develops as silica-rich groundwater fills cavities (vesicles) in lava or rock, precipitating in layers over thousands of years.

Uses & Applications

Used widely in lapidary arts, jewelry, decorative ornaments, and industrial uses like mortar and pestles due to its hardness and resistance to acids.

Geological Facts

Agate was named by the Greek philosopher Theophrastus who discovered the stone along the shore line of the Achates River in Sicily. The banding is caused by periodic changes in the concentration of silica during deposition.

Field Identification & Locations

Identify by its waxy luster, translucency, and characteristic curved banding patterns. Often found as rounded nodules on beaches or in dry riverbeds.

Identified on: 4/25/2026

Mode: Standard