Yellow Chalcedony (Agate/Jasper mix)

Physical Properties

Hardness: 6.5-7 on Mohs scale. Color: Translucent to opaque yellow, amber, and tan. Luster: Waxy to vitreous. Crystal structure: Cryptocrystalline (Trigonal/Monoclinic). Cleavage: None (conchoidal fracture). Specific Gravity: 2.58-2.64.

Formation & Geological History

Formed through the deposition of silica-rich groundwater in cavities of volcanic igneous rocks or sedimentary formations. This specimen shows signs of tumbling or weathering, likely from a riverbed or alluvial deposit.

Uses & Applications

Used primarily in lapidary arts for gemstones, cabochons, and beads. Also used for ornamental carvings and historic tools like scrapers due to its hardness and sharp fracture edges.

Geological Facts

Yellow chalcedony is often called 'Yellow Agate' if banded or 'Yellow Jasper' if opaque. It has been used by humans for over 3,000 years for seals and jewelry.

Field Identification & Locations

Identify in the field by its waxy appearance, lack of visible crystals, and inability to be scratched by a steel knife. Commonly found in river gravels, volcanic fields, and desert regions.

Identified on: 5/13/2026

Mode: Standard