mineral

Carnelian agate

Chalcedony (microcrystalline quartz), SiO₂; iron-oxide colored variety

AI-generated identification · may be incorrect

Typically translucent orange-red to brown, with a waxy to vitreous luster and conchoidal fracture; Mohs hardness 6.5–7, trigonal quartz structure, no cleavage, and specific gravity about 2.58–2.64. The specimen appears naturally rough and partly translucent, possibly brecciated or banded chalcedony.

Identified September 15, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, with iron oxides producing the orange-brown color. Most specimens are Cenozoic to older, and exact age depends on the host rock.

Uses & applications

Used for cabochons, beads, carvings, seals, and ornamental objects; durable pieces are also collected as lapidary rough. It is generally an affordable gemstone.

Geological facts

Carnelian is a cryptocrystalline quartz variety closely related to sard and agate; heating can intensify its red-orange color. Its conchoidal fracture produces sharp edges, historically useful for tools and blades.

Field identification & locations

Identify it by its orange-brown translucent body, glassy/waxy luster, lack of cleavage, and ability to scratch glass. Common sources include India, Brazil, Uruguay, Madagascar, and the United States.