gemstone

Polished carnelian (banded agate)

Chalcedony, microcrystalline quartz (SiO₂), likely iron-stained banded agate

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; vivid orange-red to pink concentric bands, waxy-to-glassy luster, cryptocrystalline structure, no visible cleavage, specific gravity about 2.6. The rounded shape indicates tumbling or polishing.

Identified August 30, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rocks, depositing layered chalcedony; iron oxides create the red-orange color. Individual bands commonly formed over millions of years, generally in Cenozoic to older volcanic settings.

Uses & applications

Used for cabochons, beads, carvings, ornaments, and inexpensive jewelry; attractive banded pieces are popular among collectors.

Geological facts

Carnelian is the orange-red variety of chalcedony, while agate is defined by visible banding. Color may be naturally enhanced or heat-treated.

Field identification & locations

Identify by its translucent edges, smooth waxy polish, hardness, and curved bands; it should resist scratching by steel but scratch glass. Common sources include Brazil, Uruguay, India, Madagascar, and the United States.