sedimentary

Jasper

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Red, brown, and tan (banded); Luster: Vitreous to waxy; Crystal structure: Microcrystalline (Trigonal); Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91

Hardness: 6
Color: Red, brown, and tan (banded)
Luster: Vitreous to waxy

Identified January 11, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the deposition of silica from mineral-rich groundwaters or volcanic ash. The red and tan patterns are caused by iron oxide (hematite) inclusions within the fine-grained quartz matrix, often appearing in sedimentary environments or as primary hydrothermal deposits.

Uses & applications

Used primarily for ornamental purposes, jewelry (cabochons and beads), lapidary art, and collectors' display specimens. It has also historically been used for making seals and amulets.

Geological facts

Jasper is an opaque variety of chalcedony. The name is derived from the Greek word 'iaspis', meaning spotted stone. It is a diverse stone with hundreds of named varieties based on color patterns and locations.

Field identification & locations

Identify in the field by its hardness (cannot be scratched by a steel pocket knife) and its smooth, waxy luster when tumbled or wet. Commonly found in riverbeds and desert environments where silica-rich minerals accumulate.