mineral

Agate

Cryptocrystalline quartz (SiO2)

Hardness 6.5-7 on Mohs scale, waxy luster, variety of colors often banded, trigonal crystal structure (microcrystalline), no cleavage, specific gravity 2.58-2.64.

Identified June 19, 2026More mineral →

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Physical properties

Hardness 6.5-7 on Mohs scale, waxy luster, variety of colors often banded, trigonal crystal structure (microcrystalline), no cleavage, specific gravity 2.58-2.64.

Formation & geological history

Formed from silica-rich groundwater filling cavities in volcanic or sedimentary rocks over thousands to millions of years.

Uses & applications

Commonly used in jewelry, ornamental carving, and lapidary arts. Historically used for hardstone carving.

Geological facts

Agate is named after the Achates River in Sicily where agates were found in antiquity.

Field identification & locations

Identified by its distinctive banding and translucency. Found worldwide, often in volcanic regions. Tips for collectors: hold up to light to see banding, check for hardness against glass.