mineral

Banded Agate

Chalcedony (SiO2) with microcrystalline quartz

Hardness: 6.5-7 Mohs; Color: White, grey, tan with concentric banding; Luster: Waxy to vitreous; Crystal Structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture).

Hardness: 6
Color: White, grey, tan with concentric banding
Luster: Waxy to vitreous

Identified April 6, 2026More mineral →

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Physical properties

Hardness: 6.5-7 Mohs; Color: White, grey, tan with concentric banding; Luster: Waxy to vitreous; Crystal Structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture).

Formation & geological history

Primary formation occurs in voids or cavities in volcanic rocks (lavas) where silica-rich groundwater deposits layers of rhythmic crystallization over thousands of years.

Uses & applications

Used extensively in jewelry, lapidary arts (cabochons), precision scales, mortar and pestles, and as decorative collectibles.

Geological facts

The concentric banding is caused by periodic changes in the silica concentration or impurities during growth. Agates are named for the Achates River in Sicily where they were first found.

Field identification & locations

Identify in the field by looking for translucent stones with 'rings' or 'bands' visible when wet. Common in gravel pits, riverbeds, and volcanic outcrops globally.

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