mineral

Banded Agate

Silicon Dioxide (SiO2) - Microcrystalline Quartz

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale), Color: Brownish-grey with visible curved banding, Luster: Vitreous to waxy, Crystal Structure: Hexagonal (trigonal) microcrystalline, Cleavage: None/Conchoidal fracture, Specific Gravity: 2.58-2.64

Hardness: 6

Identified July 12, 2026More mineral →

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Physical properties

Formation & geological history

Formed as secondary deposits in volcanic rock cavities (amygdules) or sedimentary veins. Silica-rich groundwater precipitates layers of microscopic quartz crystals over long periods.

Uses & applications

Used widely in lapidary arts, jewelry, decorative carvings, and industrially for precision pendulums, mortars and pestles due to its hardness.

Geological facts

Agate is named after the Achates River in Sicily where it was first discovered in ancient times. The banding patterns represent different stages of silica deposition in the host rock cavity.

Field identification & locations

Identified by its distinctive curved layers and translucent edges. It can be found in gravel beds, volcanic outcrops, and along shorelines of the Great Lakes (Lake Superior Agates).