gemstone

Polished banded agate (likely sardonyx/carnelian agate)

Microcrystalline quartz (chalcedony), SiO₂, with iron-oxide color bands

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent red-orange and black bands with a waxy to vitreous polish. Trigonal quartz structure at microscopic scale; no visible cleavage, conchoidal fracture; specific gravity about 2.6.

Identified October 3, 2026More gemstone →

Explore Polished banded agate (likely sardonyx/carnelian agate) in the encyclopedia →

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Physical properties

Formation & geological history

Agate forms as silica-rich fluids fill cavities and deposit successive chalcedony layers, commonly in volcanic rocks. The pictured piece is cut and polished; its age and source cannot be determined from the image.

Uses & applications

Used for jewelry, beads, carvings, and decorative objects; agate is also used for ornamental and precision components.

Geological facts

Agate’s striking bands are successive silica deposits, and iron compounds commonly produce red, orange, or brown colors.

Field identification & locations

Look for curved or parallel bands, translucency at thin edges, and a glassy/waxy polish; agate occurs worldwide, often in volcanic regions. This appears to be a small shaped cabochon or bead, but the exact variety is uncertain from the photo.