Rock Identifier
Polished carnelian agate (Microcrystalline quartz (chalcedony), SiO₂; the orange-red variety is commonly called carnelian) — gemstone
gemstone

Polished carnelian agate

Microcrystalline quartz (chalcedony), SiO₂; the orange-red variety is commonly called carnelian

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; orange, rust-red, cream and brown mottling; waxy to vitreous polish; cryptocrystalline trigonal quartz with no visible cleavage. The specimen appears tumbled and polished.

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Physical properties

Mohs hardness 6.5–7; orange, rust-red, cream and brown mottling; waxy to vitreous polish; cryptocrystalline trigonal quartz with no visible cleavage. The specimen appears tumbled and polished.

Formation & geological history

Forms as silica-rich chalcedony filling cavities and fractures, often in volcanic rocks; its precise age and source cannot be determined from the image.

Uses & applications

Used for beads, cabochons, ornaments and collecting; chalcedony also has decorative and lapidary uses.

Geological facts

Carnelian’s warm color commonly comes from iron-bearing impurities; heating can deepen or alter its hue.

Field identification & locations

Look for translucency at thin edges, waxy luster and hardness sufficient to scratch glass; common sources include India, Brazil and Uruguay.

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