Chert (Yellow Jasper)

Physical Properties

Hardness: 6.5-7 (Mohs scale); Color: Tan, yellow, ochre; Luster: Waxy to dull; Crystal structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7

Formation & Geological History

Formed through the accumulation of silica-rich micro-organisms or chemical precipitation within sedimentary layers. This specific piece shows a water-worn, tumbled surface suggesting transport in a river or creek bed.

Uses & Applications

Historically used for making stone tools; currently used for lapidary work, cabochons, and as an ornamental garden stone.

Geological Facts

Yellow jasper is often associated with solar energy in metaphysical circles; geologically, its color comes from tiny inclusions of iron oxide minerals like goethite.

Field Identification & Locations

Identify in the field by its smooth, waxy texture and conchoidal (shell-like) fractures. It will easily scratch glass but cannot be scratched by a steel knife. Common in river beds and sedimentary basins worldwide.

Identified on: 4/23/2026

Mode: Standard