mineral

Agate

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs); Color: Multi-colored bands (brown, white, green); Luster: Waxy to vitreous; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.58-2.64

Hardness: 6
Color: Multi-colored bands (brown, white, green)
Luster: Waxy to vitreous

Identified June 28, 2026More mineral →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Multi-colored bands (brown, white, green); Luster: Waxy to vitreous; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.58-2.64

Formation & geological history

Formed in volcanic rock cavities (vesicles) or metamorphic rocks where silica-rich groundwater deposits layers of chalcedony over thousands of years.

Uses & applications

Used primarily in lapidary arts, jewelry (cabochons), precision weighs, and as a collector's specimen.

Geological facts

Agate is a variety of chalcedony characterized by its fineness of grain and brightness of color. It is the official gemstone of several US states including Kentucky and Tennessee.

Field identification & locations

Identify by its translucent nature when held to light and characteristic banding or 'eye' patterns. Commonly found in riverbeds and volcanic regions worldwide.