sedimentary

Banded Agate

Cryptocrystalline Quartz (SiO2)

Hardness: 6.5-7.0 (Mohs scale), Color: White with reddish-brown banding, Luster: Waxy to vitreous, Structure: Trigonal (microcrystalline), Specific Gravity: 2.58-2.64

Hardness: 6

Identified July 8, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7.0 (Mohs scale), Color: White with reddish-brown banding, Luster: Waxy to vitreous, Structure: Trigonal (microcrystalline), Specific Gravity: 2.58-2.64

Formation & geological history

Formed in cavities within volcanic or sedimentary rocks where silica-rich groundwater deposited layers of microcrystalline quartz over thousands of years. The banding results from periodic changes in the solution chemistry.

Uses & applications

Commonly used for lapidary work, including jewelry such as beads and cabochons, as well as garden decoration, tumbling, and as emotional healing stones in alternative practices.

Geological facts

Agates are often found as nodules within volcanic rocks but can also be found as secondary deposits in riverbeds and on beaches. The word agate comes from the Achates River in Sicily, where they were first discovered.

Field identification & locations

Identified by its translucency (light can pass through edges) and the presence of fine-grained concentric or planar banding. Harder than steel; it will not be scratched by a knife blade.