Yellow Jasper (Chert)

Physical Properties

Hardness: 6.5-7 (Mohs); Color: Yellowish-brown, ochre, mustard; Luster: Dull to waxy; Crystal Structure: Trigonal (microcrystalline); Cleavage: None/Conchoidal fracture; Specific Gravity: 2.6-2.9

Formation & Geological History

Formed through the accumulation of silica-rich microfossils or chemical precipitation in sedimentary basins. The yellow color is typically due to iron (goethite or limonite) inclusions. Its geological age varies by location, often millions of years old.

Uses & Applications

Used primarily in lapidary work for cabochons, beads, and ornemental carvings. Due to its hardness and density, it is also used in tumble polishing for aquarium decor.

Geological Facts

Jasper is a microcrystalline variety of quartz. The name comes from the Greek word 'iaspis', meaning 'spotted stone'. In ancient times, it was considered a powerful protective stone.

Field Identification & Locations

Identify in the field by its hardness (cannot be scratched by a steel knife), conchoidal fracture (curved breaks), and smooth, waxy feel when wet. Found in riverbeds and mountainous regions globally.

Identified on: 5/15/2026

Mode: Standard