gemstone

Agate

Silicon Dioxide (Chalcedony), SiO2

Hardness: 6.5 - 7 on the Mohs scale. Color: White, gray, translucent with fine banding. Luster: Vitreous to waxy. Crystal structure: Trigonal (microcrystalline quartz). Cleavage: None. Specific gravity: 2.58 - 2.64.

Hardness: 6
Color: White, gray, translucent with fine banding
Luster: Vitreous to waxy

Identified August 5, 2026More gemstone →

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Physical properties

Formation & geological history

Formed by the deposition of silica from groundwater in the cavities of igneous and metamorphic rocks, typically over millions of years.

Uses & applications

Widely used in jewelry making as cabochons, carved ornaments, decorative items, and metaphysical practices.

Geological facts

Agate has been used since ancient times, notably by the ancient Greeks and Romans for intaglio rings and medicinal amulets.

Field identification & locations

Easily identified by its distinctive concentric color banding and translucent appearance. Found worldwide, with major deposits in Brazil, Uruguay, India, and the USA.