mineral

Agate

Silicon Dioxide (SiO2)

Hardness: 6.5-7 Mohs; Color: Brown, Amber, Translucent; Luster: Waxy to Vitreous; Crystal Structure: Trigonal (Microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Hardness: 6
Color: Brown, Amber, Translucent
Luster: Waxy to Vitreous

Identified June 28, 2026More mineral →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Brown, Amber, Translucent; Luster: Waxy to Vitreous; Crystal Structure: Trigonal (Microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Formation & geological history

Formed as a secondary mineral in volcanic rock cavities (vesicles) through the deposition of silica from groundwater. Most specimens range from hundreds of thousands to millions of years old.

Uses & applications

Widely used in jewelry (cabochons), precision weighing balances, mortars and pestles, and as decorative pocket stones or healing crystals.

Geological facts

Agate was named by Theophrastus, a Greek philosopher, who discovered the stone along the shore line of the Dirillo River in Sicily. It is characterized by its fineness of grain and brightness of color.

Field identification & locations

Identify by its translucency when held to light and its waxy luster. Common in river beds, beaches, and volcanic regions. Collectors look for unique banding or moss-like inclusions.