sedimentary

Agate

Silicon Dioxide (Chalcedony), SiO2

AI-generated identification · may be incorrect

Hardness: 6.5-7 on the Mohs scale; Color: Varied, including white, gray, blue, red, green, and brown; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline quartz); Cleavage: None; Specific gravity: 2.58-2.64

Hardness: 6
Color: Varied, including white, gray, blue, red, green, and brown
Luster: Waxy to vitreous

Identified July 30, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed primarily within cavities of volcanic and metamorphic rocks through the deposition of silica from groundwater solutions in rhythmic bands over geological time.

Uses & applications

Used in ornamental objects, jewelry, carving, and as a collector's specimen.

Geological facts

Agate is named after the Achates River in Sicily, where stones were found in ancient times. It has been used for seals, signet rings, and ornamentation since ancient civilizations.

Field identification & locations

Identified by its distinctive banding patterns, waxy luster, and conchoidal fracture. Commonly found in regions with ancient volcanic activity worldwide.