sedimentary

Tumbled Agate

Agate (Cryptocrystalline variety of Quartz, SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Multi-colored with banding (this specimen shows reddish-brown/purple tones); Luster: Vitreous to waxy; Crystal structure: Trigonal/Hexagonal (microscopic); Specific gravity: 2.58-2.64.

Hardness: 6
Luster: Vitreous to waxy

Identified July 1, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in cavities (vugs) within volcanic rock or ancient lavas. They are created when silica-rich groundwater percolates through these openings over millions of years, depositing layers of chalcedony.

Uses & applications

Used primarily in jewelry, lapidary arts, decorative items, and as healing stones in metaphysical practices. Historically used for making mortars and pestles.

Geological facts

Agate is named after the Achates River in Sicily where it was first discovered. The banding characteristic of agate is caused by rhythmic crystallization of silica layers.

Field identification & locations

Identify in the field by its waxy luster and translucency when held to light. Often found as nodules with a rough exterior but reveal beautiful banding when sliced or tumbled. Common in Brazil, India, and the Lake Superior region.

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