mineral

Carnelian (Chalcedony)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale. Color: Orange to reddish-brown. Luster: Vitreous to waxy. Crystal Structure: Hexagonal (trigonal) microcrystalline. Cleavage: None (conchoidal fracture). Specific Gravity: 2.58-2.64.

Hardness: 6
Color: Orange to reddish-brown
Luster: Vitreous to waxy

Identified April 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed in volcanic environments as silica-rich fluids precipitate into cavities or gas bubbles (amygdules) within lava. Iron oxide impurities provide the red-orange coloring. They are often found as weathered pebbles in riverbeds.

Uses & applications

Predominantly used as a gemstone for jewelry (cabochons, beads), decorative carvings, and in lapidary arts. Historically used for seal stones and amulets.

Geological facts

Carnelian was highly prized in ancient times; ancient Romans used it for signet rings because hot wax does not stick to it. It has been found in archaeological sites dating back to the Neolithic period.

Field identification & locations

Identify by its translucency (when held to light), waxy luster, and lack of visible crystalline structure. Often found in gravel deposits, stream beds, or coastal areas like those in Brazil, India, or the US Pacific Northwest.