mineral

Polished banded agate (likely blue lace agate)

Chalcedony, microcrystalline SiO₂, with iron and other trace-element impurities

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent blue-gray, white, brown, and reddish bands; waxy to vitreous luster; cryptocrystalline quartz with no cleavage, conchoidal fracture, and typical specific gravity around 2.6. The specimen is cut and polished, with pronounced concentric fortification banding.

Identified August 15, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rocks, depositing successive layers of chalcedony over long periods, commonly during the Cenozoic or older volcanic episodes. Blue lace agate is especially associated with Namibia, while similarly patterned agates occur worldwide.

Uses & applications

Used for cabochons, beads, carvings, ornaments, and decorative objects; its toughness makes it suitable for jewelry. It has modest collector value, increasing with vivid color, sharp banding, translucency, and polish.

Geological facts

Agate is a variety of chalcedony rather than a separate mineral species. Its intricate banding records changing chemistry and flow conditions during cavity filling.

Field identification & locations

Identify it by hard, curved fracture, waxy translucency, and fine rhythmic bands; it should not scratch easily with a steel knife. Common sources include Brazil, Uruguay, Mexico, Namibia, India, and the United States.