mineral

Agate

Agatized Chalcedony (SiO2)

Hardness: 6.5-7 (Mohs). Color: Multi-colored bands, translucent to opaque. Luster: Waxy to vitreous. Crystal structure: Cryptocrystalline. Cleavage: None, conchoidal fracture. Specific gravity: 2.60-2.65.

Hardness: 6
Color: Multi-colored bands, translucent to opaque
Luster: Waxy to vitreous

Identified June 7, 2026More mineral →

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Physical properties

Formation & geological history

Formed primarily within volcanic and metamorphic rocks. It develops in rock cavities (geodes) via the deposition of silica from groundwater over thousands to millions of years.

Uses & applications

Commonly used in jewelry (cabochons, beads), decorative carvings, and industrial mill balls due to its hardness and resistance to chemicals.

Geological facts

Agate is named after the Achates River in Sicily where it was first discovered. Every agate is unique due to the specific mineral impurities and pressure changes during its formation.

Field identification & locations

Identify by its waxy luster, conchoidal fracture (curved glass-like breaks), and banding when sliced. Found globally in riverbeds, lake shores (like Lake Superior), and volcanic outcrops.