gemstone

Polished carnelian agate

Microcrystalline quartz (chalcedony), SiO₂, with iron-oxide coloration

AI-generated identification · may be incorrect

Orange-red, translucent, waxy to vitreous luster with faint curved or banded agate structure. Mohs hardness 6.5–7; trigonal quartz structure, no cleavage, conchoidal fracture; specific gravity about 2.6.

Identified September 13, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rocks, depositing chalcedony in layers; iron oxides create the red-orange color. Most specimens are Cenozoic to older, depending on the host volcanic rocks.

Uses & applications

Used for beads, cabochons, carvings, seals, and ornamental objects; durable and attractive but generally modestly valued.

Geological facts

Carnelian is the red-orange variety of chalcedony, while visible banding or patterns indicate agate. Heating can intensify its color, and some commercial material is dyed.

Field identification & locations

Identify by its orange-red translucent body, waxy polish, hardness, and lack of cleavage; glass often shows bubbles and scratches more easily. Common sources include India, Brazil, Uruguay, Madagascar, and Botswana.