mineral

Banded Agate

Chalcedony (SiO2) with impurities

Hardness: 6.5-7 on Mohs scale; Color: Reddish-brown, tan, and translucent white bands; Luster: Waxy to vitreous; Crystal Structure: Microcrystalline/Trigonal (Cryptocrystalline); Cleavage: None; Fracture: Conchoidal.

Hardness: 6
Color: Reddish-brown, tan, and translucent white bands
Luster: Waxy to vitreous

Identified June 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed primarily in volcanic environments where silica-rich groundwater fills cavities (vesicles) in lava. The concentric banding is caused by the rhythmic deposition of silica over thousands of years.

Uses & applications

Used extensively in jewelry (cabochons, beads), decorative carvings, and as a semi-precious collector gemstone. Historically used for making mortars and pestles due to hardness.

Geological facts

Agate is a variety of chalcedony. The name 'Agate' was given by the Greek philosopher Theophrastus, who discovered the stone along the shore of the Dirillo River in Sicily.

Field identification & locations

Identify by the characteristic waxy luster and concentric or parallel banding when held to light. Often found in riverbeds or areas with weathered volcanic rock. Collectors value high-contrast banding.