mineral

White Agate (Chalcedony)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on the Mohs scale. Color: Translucent white to milky white. Luster: Waxy to vitreous. Crystal structure: Trigonal (microcrystalline). Cleavage: None (conchoidal fracture). Specific gravity: 2.60–2.64.

Hardness: 6
Color: Translucent white to milky white
Luster: Waxy to vitreous

Identified March 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica from groundwater in the cavities of igneous rocks, particularly volcanic lavas. Geologically, agates can range from thousands to millions of years old depending on the host rock formation.

Uses & applications

Commonly used in the production of semiprecious jewelry (beads, cabochons), ornamental carvings, and industrial mortars/pestles due to its hardness and chemical resistance.

Geological facts

Agate is a variety of chalcedony. It was named by Theophrastus, a Greek philosopher, who discovered the stone along the shore line of the river Achates (now Dirillo) in Sicily. It is often treated or dyed to achieve different colors.

Field identification & locations

Identify in the field by its waxy luster, smooth texture (especially when river-worn), and lack of cleavage. Often found in riverbeds, desert landscapes, and volcanic regions. Common locations include Brazil, India, and the Lake Superior region of the USA.