Jasper (Green Jasper / Chert)

Physical Properties

Hardness: 6.5-7 on Mohs scale; Color: Dark olive green; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.9.

Formation & Geological History

Formed through the accumulation of silica-rich fluids in volcanic or sedimentary environments. Most jasper dates back to the Precambrian or Paleozoic eras.

Uses & Applications

Used primarily for ornamental purposes, jewelry (cabochons), lapidary art, and rock tumbling. Historically used for making tools due to its sharp fracture edges.

Geological Facts

Green jasper was a favorite in the ancient world, often called 'rain bringer' and used in amulets. It is an opaque variety of chalcedony.

Field Identification & Locations

Identify in the field by its smooth, waxy surface when wet and its sharp, shell-like (conchoidal) breakage patterns. It cannot be scratched by a steel knife. Commonly found in riverbeds and coastal areas.

Identified on: 4/17/2026

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