Yellow Chalcedony (Agate)

Physical Properties

Hardness: 6.5-7 on Mohs scale; Color: Translucent yellowish-brown to honey; Luster: Waxy to vitreous; Crystal Structure: Cryptocrystalline (hexagonal); Cleavage: None; Specific Gravity: 2.6-2.64

Formation & Geological History

Formed through the deposition of silica from groundwater in cavities of volcanic or sedimentary rocks. It often precipitates at relatively low temperatures.

Uses & Applications

Used primarily in jewelry as gemstones, cabochons, and beads. Also used for ornamental carvings, seals, and historically for stone tools due to its conchoidal fracture.

Geological Facts

This specimen appears to be water-worn, likely found in a riverbed or coastal area. Chalcedony is a broad term that includes agate, onyx, and jasper.

Field Identification & Locations

Identify by its waxy luster, translucency when held to light, and lack of visible crystals. It cannot be scratched by a steel knife. Common in volcanic regions and gravel deposits.

Identified on: 4/13/2026

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