mineral

Banded Agate

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs scale), Color: Cream, white, and tan concentric banding, Luster: Waxy to vitreous, Crystal structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture).

Hardness: 6

Identified July 21, 2026More mineral →

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Physical properties

Hardness: 6.5-7 (Mohs scale), Color: Cream, white, and tan concentric banding, Luster: Waxy to vitreous, Crystal structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture).

Formation & geological history

Formed in volcanic rock cavities or ancient sedimentary layers through the gradual deposition of silica from groundwater. Most agates are millions of years old, often dating to the Cenozoic or Mesozoic eras.

Uses & applications

Primarily used for lapidary work, jewelry, pocket stones, and decorative carvings. Industrially used for precision pendulums and laboratory mortars/pestles due to its hardness.

Geological facts

Agate is a variety of chalcedony. The banding is caused by the rhythmic crystallization of silica over long periods of time. It was named by Theophrastus after the Achates River in Sicily.

Field identification & locations

Identify by looking for translucent to opaque layers and concentric banding. Commonly found in gravel beds, river banks, and volcanic regions. Use a flashlight to check for translucency.