mineral

Banded Agate

Chalcedony (Silicon Dioxide, SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Reddish-brown, white, and translucent; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.64.

Hardness: 6
Color: Reddish-brown, white, and translucent
Luster: Waxy to vitreous

Identified May 11, 2026More mineral →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Reddish-brown, white, and translucent; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.64.

Formation & geological history

Formed primarily in volcanic and metamorphic rocks. Most agates occur as nodules in volcanic rocks or ancient lavas, where silica-rich groundwater fills cavities and precipitates in layers over time.

Uses & applications

Used extensively in jewelry making, ornamental carvings, gemstones, and historically for precision mechanical parts like knife-edge bearings for laboratory balances.

Geological facts

Agate is named after the Achates River in Sicily where it was first discovered. The banding patterns are often uniquely rhythmic and act as a geological fingerprint of the environment present during formation.

Field identification & locations

Identified by its translucency, concentric banding, and waxy surface when polished. Commonly found in Brazil, India, and the Lake Superior region of the USA. Field identification relies on hardness and the lack of cleavage.