mineral

Dyed blue banded agate

Microcrystalline quartz (SiO₂), mainly chalcedony

AI-generated identification · may be incorrect

Polished/tumbled, translucent gray-blue with concentric blue and cream banding; vitreous to waxy luster, hardness 6.5–7 Mohs, no cleavage, cryptocrystalline structure, specific gravity about 2.6.

Identified August 31, 2026More mineral →

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Physical properties

Polished/tumbled, translucent gray-blue with concentric blue and cream banding; vitreous to waxy luster, hardness 6.5–7 Mohs, no cleavage, cryptocrystalline structure, specific gravity about 2.6.

Formation & geological history

Agate forms when silica-rich groundwater fills vesicles in volcanic rock, depositing chalcedony and quartz in successive layers. The host rocks are commonly Cenozoic to older volcanic flows; vivid blue coloration is often enhanced by dyeing.

Uses & applications

Used for cabochons, jewelry, carvings, ornamental objects, and lapidary collections; agate is durable and takes an excellent polish.

Geological facts

Natural agate colors are typically gray, white, brown, or orange; intensely uniform blue commonly indicates treatment. Concentric banding records changing chemistry during cavity filling.

Field identification & locations

Identify it by curved banding, translucency, waxy polish, and glass-like hardness; it should scratch ordinary glass but not be scratched by a steel blade. Common sources include Brazil, Uruguay, Mexico, India, and Madagascar.