Jasper

Physical Properties

Hardness: 6.5-7 (Mohs scale); Color: Brown, yellow, ochre, reddish; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None, conchoidal fracture

Formation & Geological History

Formed from silica-rich fluids trickling through cracks in other rocks or ash, often enriched with iron and other mineral impurities during the deposition process. Can be found in volcanic as well as sedimentary environments.

Uses & Applications

Used primarily in lapidary work for cabochons, beads, and stone carvings. Historically used for making tools due to its hardness and sharpness when fractured.

Geological Facts

Jasper is an opaque variety of chalcedony. The name 'jasper' is derived from the Greek word 'iaspis', meaning 'spotted stone'. It is known for its wide variety of patterns and colors caused by mineral inclusions.

Field Identification & Locations

Identify in the field by its hardness (cannot be scratched by a steel knife), opaque quality (does not let light through even on thin edges), and conchoidal fracture. Commonly found in riverbeds and desert environments.

Identified on: 4/20/2026

Mode: Standard