sedimentary

Jasper

Silicon dioxide (SiO2) with iron oxide inclusions

Hardness: 6.5-7 (Mohs); Color: Yellow, mustard, ochre with red mottling; Luster: Dull to waxy; Crystal Structure: Microcrystalline/Trigonal (Cryptocrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91

Hardness: 6
Color: Yellow, mustard, ochre with red mottling
Luster: Dull to waxy

Identified July 13, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the deposition of silica-rich fluids in volcanic or sedimentary environments, often involving the replacement of organic materials or minerals by silica. The yellow and red colors are caused by goethite and hematite inclusions.

Uses & applications

Widely used for lapidary work, including cabochons, beads, and carvings. Also used as a decorative stone and historically for seals and tools.

Geological facts

Jasper is an opaque variety of chalcedony. The name comes from the Greek word 'iaspis', meaning 'spotted stone.' It has been used by ancient civilizations for jewelry and amulets for thousands of years.

Field identification & locations

Identify in the field by its hardness (cannot be scratched by a steel knife), opaque nature, and smooth, shell-like (conchoidal) fracture surfaces. Common in riverbeds and desert environments globally.

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