Chalcedony (Carnelian variety)

Physical Properties

Hardness: 6.5-7 on Mohs scale; Color: Reddish-brown to orange-brown; Luster: Waxy to vitreous; Crystal Structure: Trigonal (cryptocrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Formation & Geological History

Forms in volcanic rocks where silica-rich fluids fill cavities (amygdales) or through low-temperature deposition in sedimentary environments. Common in post-Cretaceous basaltic flows.

Uses & Applications

Used primarily in lapidary work, jewelry (beads, cabochons), carvings, and as a popular collector's specimen due to its translucency and color.

Geological Facts

Carnelian has been used as a gemstone since the Early Neolithic period; it was highly prized in Ancient Egypt for amulets and in Rome for signet rings because it doesn't stick to hot wax.

Field Identification & Locations

Identify by its waxy luster, conchoidal fracture (curved breaks), and reddish-brown translucency. Often found in riverbeds or coastal gravels in areas with ancient volcanic activity.

Identified on: 5/14/2026

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