mineral

Red chalcedony (likely dyed or heat-treated)

Microcrystalline quartz, SiO₂; possibly red agate/carnelian

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent red-orange, waxy to vitreous luster, cryptocrystalline quartz, no cleavage, conchoidal fracture, specific gravity about 2.6. The rough, glossy appearance and uniform vivid color may indicate polishing, dyeing, or treatment.

Identified August 22, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, commonly during the Cenozoic or older volcanic episodes. Red color generally comes from iron oxides or artificial treatment.

Uses & applications

Used for cabochons, beads, carvings, ornaments, and small decorative specimens; poorer material is used in inexpensive lapidary work.

Geological facts

Carnelian is the orange-red variety of chalcedony, while red agate commonly shows banding; this specimen appears largely unbanded. Identification should be confirmed with a hardness, magnification, and dye-penetration test.

Field identification & locations

Common in Brazil, Uruguay, India, Madagascar, Mexico, and the United States. It should scratch glass but not be scratched by a steel knife; natural agate often shows bands or color variation.