mineral

Banded Agate

Silicon dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Gray, blue, and tan bands; Luster: Waxy to vitreous; Crystal Structure: Trigonal (cryptocrystalline); Cleavage: None; Fracture: Conchoidal.

Hardness: 6
Color: Gray, blue, and tan bands
Luster: Waxy to vitreous

Identified July 12, 2026More mineral →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Gray, blue, and tan bands; Luster: Waxy to vitreous; Crystal Structure: Trigonal (cryptocrystalline); Cleavage: None; Fracture: Conchoidal.

Formation & geological history

Formed from silica-rich groundwater filling cavities in volcanic rocks (like basalt) or sedimentary host rocks. The bands represent different pulses of mineral deposition over thousands of years.

Uses & applications

Polished for jewelry (cabochons), used in ornamental carvings, as a collector specimen, and historically for precision mechanical parts like mortars and pestles.

Geological facts

The name Agate comes from the Achates River in Sicily, where agates were first discovered. No two agates are exactly alike due to the unique layering process of microcrystalline quartz.

Field identification & locations

Identify by its waxy texture and characteristic concentric banding. Common in volcanic regions worldwide, especially in Brazil, Uruguay, and the Lake Superior region of the USA.