mineral

Banded Agate (often called Brown Agate or Chalcedony)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on the Mohs scale; Color: Brown, tan, and white translucent bands; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific gravity: 2.58–2.64.

Hardness: 6
Color: Brown, tan, and white translucent bands
Luster: Vitreous to waxy

Identified February 5, 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 such as basalt or volcanic tuff. Over millions of years, the silica layers solidify into the banded pattern seen.

Uses & applications

Commonly used in jewelry (cabochons and beads), decorative ornaments, and industrial applications like mortar and pestles due to its hardness and chemical resistance.

Geological facts

The name 'Agate' comes from the Achates River in Sicily, where agates were first discovered by ancient Greeks. They have been used as amulets for protection throughout human history.

Field identification & locations

Identify in the field by its distinct concentric or wavy color banding and its waxy luster when broken. It is commonly found in Brazil, India, and the Lake Superior region of the USA. Look for translucency and the absence of cleavage.

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