sedimentary

Agate

Silicon dioxide (SiO2) - Chalcedony variety

AI-generated identification · may be incorrect

Hardness: 6.5 to 7 on the Mohs scale. Color: Brown, gray, white, yellow, and translucent banded patterns. Luster: Vitreous to waxy. Crystal structure: Trigonal/Microcrystalline quartz. Cleavage: None, exhibits conchoidal fracture. Specific gravity: 2.6 to 2.7.

Hardness: 6
Color: Brown, gray, white, yellow, and translucent banded patterns
Luster: Vitreous to waxy

Identified August 7, 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-rich groundwater solutions in concentric layers over millions of years.

Uses & applications

Used in jewelry, ornamental carvings, lapidary art, industrial bearings, and mortar and pestle sets due to its hardness and durability.

Geological facts

Agate was highly prized in antiquity as a healing stone and amulet, famously used by the ancient Greeks and Romans for intaglio rings and ornate vessels.

Field identification & locations

Identified easily by its distinctive waxy luster, microcrystalline structure, conchoidal fracture, and characteristic concentric banding. Found worldwide, notably in Brazil, the USA, and Germany. Highly accessible to collectors.