mineral

Agate

Chalcedony (SiO2)

Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, conchoidal fracture, cryptocrystalline quartz structure, transparent to opaque with banded or multicolored patterns.

Identified August 7, 2026More mineral →

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Physical properties

Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, conchoidal fracture, cryptocrystalline quartz structure, transparent to opaque with banded or multicolored patterns.

Formation & geological history

Formed mainly in cavities of volcanic and metamorphic rocks through the slow deposition of silica-rich groundwater over millions of years.

Uses & applications

Used in jewelry, ornamental carvings, lapidary arts, precision instruments, and as mineral collecting specimens.

Geological facts

Agates were named by the ancient Greek philosopher Theophrastus after the Achates River in Sicily where he found them. They often preserve ancient water droplets trapped inside.

Field identification & locations

Easily identified by their distinctive curved or concentric banding and waxy luster. Found worldwide, particularly in regions with past volcanic activity such as Brazil, India, and the United States (Lake Superior region).