sedimentary

Banded Agate

Cryptocrystalline Quartz (SiO2)

Hardness: 6.5-7 on Mohs scale. Color: Tan, orange, and white bands. Luster: Waxy to vitreous. Crystal structure: Trigonal/Microcrystalline. Specific gravity: 2.58-2.64.

Hardness: 6
Color: Tan, orange, and white bands
Luster: Waxy to vitreous

Identified July 6, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 on Mohs scale. Color: Tan, orange, and white bands. Luster: Waxy to vitreous. Crystal structure: Trigonal/Microcrystalline. Specific gravity: 2.58-2.64.

Formation & geological history

Formed primarily in volcanic environments where silica-rich groundwater fills cavities in igneous rocks. The layers form rhythmically over time. These specimens often date back 50 million to 1 billion years depending on location.

Uses & applications

Commonly used in jewelry (cabochons, beads), decorative objects, tumbled stones for collectors, and historically for precision instruments like mortars and pestles due to hardness.

Geological facts

Agate is named after the Achates River in Sicily, where it was first discovered. The 'fortification' pattern seen here mimics the ancient walls of a fortress.

Field identification & locations

Identify by its characteristic colorful banding and translucent edges. Commonly found in riverbeds or beaches in regions like Lake Superior, Brazil, and India. It is much harder than common river glass or plastic.