mineral

Red Agate

Agate (Cryptocrystalline variety of Quartz, SiO2)

Hardness: 6.5–7 on Mohs scale; Color: Red to brownish-red with visible banding; Luster: Waxy to vitreous; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific gravity: 2.58–2.64.

Hardness: 6
Color: Red to brownish-red with visible banding
Luster: Waxy to vitreous

Identified April 6, 2026More mineral →

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Physical properties

Formation & geological history

Formed primarily in volcanic and metamorphic rocks as silica-rich groundwater fills cavities (vesicles or gas bubbles). As layers of silica precipitate out over time, the distinct banding develops. Age varies from recent to hundreds of millions of years.

Uses & applications

Widely used in jewelry (beads, cabochons), carvings, and decorative items. Historically used for making mortar and pestles due to its hardness and chemical resistance. Frequently used in lapidary arts and as a collector's stone.

Geological facts

Agate was named by Theophrastus, a Greek philosopher, who discovered the stone along the Achates River in Sicily. Red agate specifically has been used in amulets since ancient times to protect against 'the evil eye.'

Field identification & locations

Identify in the field by its distinct concentric banding, waxy luster when broken, and inability to be scratched by a steel knife. Common locations include Brazil, Uruguay, India, and the Lake Superior region of the United States.

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