Rock Identifier
Banded Agate (Tumbled Chalcedony) (Silicon Dioxide (SiO2)) — mineral
mineral

Banded Agate (Tumbled Chalcedony)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on the Mohs scale. Luster: Waxy to vitreous. Color: Creamy white, tan, grayish-brown with dark brown to black banding. Structure: Microcrystalline quartz (trigonal system). Specific gravity: ~2.6.

Hardness
6
Luster
Waxy to vitreous
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Physical properties

Hardness: 6.5-7 on the Mohs scale. Luster: Waxy to vitreous. Color: Creamy white, tan, grayish-brown with dark brown to black banding. Structure: Microcrystalline quartz (trigonal system). Specific gravity: ~2.6.

Formation & geological history

Formed in cavities within volcanic or metamorphic rocks when silica-rich hydrothermal fluids precipitate layers of microcrystalline quartz over long geological periods.

Uses & applications

Popular for lapidary arts, wire-wrapping, jewelry making, polished stone collections, and ornamental crafts.

Geological facts

Agate is named after the Achates River (now the Dirillo River) in Sicily, where it was discovered by ancient Greeks. Each banded specimen is unique due to varying trace mineral inclusions during formation.

Field identification & locations

Identified by its smooth, polished texture, translucent to opaque body, and characteristic layered banding patterns. Commonly found along riverbeds, beaches, and weathered volcanic rock deposits worldwide, including the US, Brazil, and Madagascar.

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