Agate

Physical Properties

Hardness: 6.5-7 (Mohs scale), Color: Translucent tan to light brown, Luster: Vitreous to waxy, Crystal Structure: Hexagonal (cryptocrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.58–2.64

Formation & Geological History

Formed as a secondary mineral in host rock cavities through the deposition of silica from groundwater; commonly found in volcanic and certain metamorphic rocks.

Uses & Applications

Used in jewelry (cabochons, beads), decorative objects, precision pendulums, and industrial applications like mortar and pestles due to its hardness.

Geological Facts

Agate is a variety of chalcedony. The name comes from the Achetes River in Sicily, where agates were first discovered in ancient times.

Field Identification & Locations

Identify by its waxy luster, translucency, and smoothness after being water-worn or tumbled. Common in riverbeds and beaches in volcanic regions.

Identified on: 5/5/2026

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