sedimentary

Banded Agate

Cryptocrystalline Quartz (SiO2)

Hardness: 6.5-7 Mohs; Color: Brown, tan, white, and reddish bands; Luster: Waxy to vitreous; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture).

Hardness: 6
Color: Brown, tan, white, and reddish bands
Luster: Waxy to vitreous

Identified July 17, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Brown, tan, white, and reddish bands; Luster: Waxy to vitreous; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture).

Formation & geological history

Formed primarily within cavities of volcanic or metamorphic rocks where silica-rich groundwater deposits layers of chalcedony over time.

Uses & applications

Used extensively in jewelry as cabochons, for ornamental carvings, paperweights, and as wear-resistant mortar and pestles in laboratories.

Geological facts

Agate is named after the Achates River in Sicily. Each agate is unique because the banding patterns are formed by varying trace elements during deposition.

Field identification & locations

Identified by its distinctive concentric or parallel banding and translucency. Commonly found in riverbeds, glaciated areas, and volcanic regions globally.