mineral

Jasper

Jasper (Silicon Dioxide, SiO2)

Hardness: 6.5-7 (Mohs); Color: Reddish-brown due to iron inclusions; Luster: Dull to vitreous; Crystal Structure: Microcrystalline (Trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91

Hardness: 6
Color: Reddish-brown due to iron inclusions
Luster: Dull to vitreous

Identified June 17, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the infiltration of silica-rich fluids into volcanic ash or fine-grained sediments, often during the Proterozoic or Paleozoic eras. The iron oxides provide the distinct red coloring during hydrothermal processes.

Uses & applications

Commonly used in lapidary work for cabochons, jewelry beads, decorative ornaments, and as a semi-precious gemstone. Also popular in rock tumbling.

Geological facts

Jasper is an opaque variety of chalcedony. It has been used since antiquity as a gemstone and for carving seals. The name comes from the Greek word 'iaspis', meaning 'spotted stone'.

Field identification & locations

Identify by its opacity (it does not transmit light even on thin edges), its smooth conchoidal fracture, and its inability to be scratched by a steel knife. Frequently found in riverbeds and coastal areas where harder rocks accumulate.