mineral

Polished banded agate (likely Botswana agate)

Microcrystalline quartz, SiO₂ (chalcedony with iron-oxide and other mineral bands)

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; gray, brown, and cream translucent bands; waxy to vitreous luster; cryptocrystalline quartz with no visible cleavage, conchoidal fracture, and specific gravity about 2.6.

Identified August 11, 2026More mineral →

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Physical properties

Hardness 6.5–7 Mohs; gray, brown, and cream translucent bands; waxy to vitreous luster; cryptocrystalline quartz with no visible cleavage, conchoidal fracture, and specific gravity about 2.6.

Formation & geological history

Forms when silica-rich groundwater repeatedly fills cavities in volcanic rocks, depositing rhythmic chalcedony layers. Individual bands may form over millions of years, commonly in Paleozoic–Mesozoic volcanic terrains.

Uses & applications

Used for cabochons, beads, carvings, ornaments, and lapidary specimens; its durability makes it suitable for jewelry and decorative objects.

Geological facts

Agate banding reflects changing chemistry, impurities, and growth conditions during cavity filling. The pictured piece is polished and appears tumbled or cabochon-shaped.

Field identification & locations

Identify by curved, parallel translucent bands, waxy luster, and lack of cleavage; verify with a hardness test or loupe, while dyes and treatments are common. Notable sources include Botswana, Brazil, Uruguay, India, Mexico, and the United States.