mineral

Polished carnelian agate

Microcrystalline quartz, SiO₂, commonly chalcedony with iron-oxide coloring

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent reddish-orange, brown, gray, and cream banding; waxy to vitreous luster; cryptocrystalline quartz with no visible cleavage. The rounded, polished form appears carved or heavily shaped.

Identified September 16, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rock, depositing chalcedony and quartz in successive bands; iron oxides create the red-orange colors. Agate commonly formed in Paleozoic–Cenozoic volcanic environments, though the specimen’s age cannot be determined visually.

Uses & applications

Used for cabochons, beads, carvings, ornaments, and lapidary objects; durable but not usually high-value jewelry material.

Geological facts

Carnelian is the red-orange variety of chalcedony, while agate is defined by banding. Color may be natural or enhanced by heat treatment and dyeing.

Field identification & locations

Identify by curved concentric bands, translucency, very fine grain, and hardness sufficient to scratch glass; acid does not fizz. Common sources include Brazil, Uruguay, India, Madagascar, and Mexico.