mineral

Chalcedony (Carnelian/Agate)

Silicon Dioxide (SiO2)

Hardness: 6.5-7. Color: Yellowish-orange to reddish-brown. Luster: Waxy to vitreous. Crystal Structure: Trigonal (microcrystalline quartz). Cleavage: None. Specific Gravity: 2.58-2.64.

Hardness: 6
Color: Yellowish-orange to reddish-brown
Luster: Waxy to vitreous

Identified July 18, 2026More mineral →

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Physical properties

Hardness: 6.5-7. Color: Yellowish-orange to reddish-brown. Luster: Waxy to vitreous. Crystal Structure: Trigonal (microcrystalline quartz). Cleavage: None. Specific Gravity: 2.58-2.64.

Formation & geological history

Formed through the deposition of silica-rich groundwater in the pockets of volcanic or sedimentary rocks, often occurring in hydrothermal veins or as nodules.

Uses & applications

Commonly used in jewelry as cabochons, for ornamental carvings, and historical use in seal stones and talismans.

Geological facts

Carnelian has been used as a gemstone since the Early Neolithic. It was famously used by the Ancient Egyptians in funerary jewelry and by Romans for signet rings because hot wax does not stick to it.

Field identification & locations

Look for a microcrystalline texture with a waxy surface and translucent to semi-opaque light passage. Often found in riverbeds or coastal areas as water-worn pebbles.