mineral

Tumbled Agate

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Brown, grey, translucent with banding/inclusions; Luster: Vitreous to waxy; Crystal structure: Hexagonal (cryptocrystalline); Specific gravity: 2.58–2.64

Hardness: 6
Color: Brown, grey, translucent with banding/inclusions
Luster: Vitreous to waxy

Identified July 18, 2026More mineral →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Brown, grey, translucent with banding/inclusions; Luster: Vitreous to waxy; Crystal structure: Hexagonal (cryptocrystalline); Specific gravity: 2.58–2.64

Formation & geological history

Formed as a secondary mineral in volcanic rock cavities or ancient sedimentary deposits. Silicate-rich groundwater leaches into voids and slowly crystallizes over thousands of years.

Uses & applications

Commonly used in jewelry, ornamental carvings, tumbled stones for collectors, and historically for precision tools or mechanical seals due to its hardness.

Geological facts

Agate is a variety of chalcedony. The name 'agate' comes from the Achates River (now Dirillo River) in Sicily, where stones were found in ancient times.

Field identification & locations

Identify in the field by its translucency and characteristic banding or moss-like inclusions. Commonly found in riverbeds, beaches, and volcanic regions globally (e.g., Brazil, USA, Madagascar).