Amber Chert (Jasper)

Physical Properties

Hardness: 6.5–7 (Mohs scale); Color: Yellow-brown, tan, or honey; Luster: Waxy to dull; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.6

Formation & Geological History

Formed through the accumulation of silica-rich organic remains or chemical precipitation in sedimentary environments. Common in marine limestone beds as nodules or replacement deposits.

Uses & Applications

Used for making cutting tools historically; currently used in jewelry (cabochons), as an ornamental stone, and for specimen collecting.

Geological Facts

Chert is so durable that it can survive long-distance transport in rivers and is often found as rounded river cobbles. It was one of the primary materials used by prehistoric humans for stone tools.

Field Identification & Locations

Identify by its waxy luster, extreme hardness (scratches glass), and shell-like (conchoidal) breakage patterns. Common in gravel pits or river beds where limestone has weathered away.

Identified on: 4/26/2026

Mode: Standard