mineral

Agate

Silicon dioxide (SiO2)

Hardness: 6.5-7 Mohs; Color: Varied bandings of black, brown, white, and translucent; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.60-2.65

Hardness: 6
Color: Varied bandings of black, brown, white, and translucent
Luster: Vitreous to waxy

Identified June 3, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica from groundwater into the cavities of igneous rocks, primarily volcanic lava, over thousands of years.

Uses & applications

Commonly used for lapidary work, jewelry (cabochons), burnishing tools, chemical mortars, and as decorative collector pieces.

Geological facts

Agate often forms in concentric layers or moss-like patterns. Ancient civilizations used them as amulets for protection and to ward off storms.

Field identification & locations

Identify by its waxy luster, translucency when held to light, and typical 'turtle shell' or banded pattern. Common in riverbeds and volcanic regions like Oregon or Brazil.