sedimentary

Jasper

Jasper (Silicon Dioxide, SiO2)

Hardness: 6.5-7 (Mohs scale), Color: Reddish-brown to maroon due to iron oxide impurities, Luster: Dull to waxy, Crystal Structure: Microcrystalline (Cryptocrystalline) hexagonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.58-2.91

Hardness: 6

Identified May 10, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the infiltration of silica-rich fluids into volcanic ash or fine-grained sediments (mostly sedimentary origins, occasionally metamorphic). Iron oxides provide the deep red pigment. Often found in Precambrian formations.

Uses & applications

Used widely in lapidary work, jewelry (cabochons, beads), decorative ornaments, and as a durable material for historical tools like scrapers and arrowheads.

Geological facts

Jasper is an opaque variety of chalcedony. The name comes from the Greek 'iaspis', meaning 'spotted stone.' It has been used historically as a gemstone and for ritualistic purposes by numerous ancient cultures including the Babylonians and Egyptians.

Field identification & locations

Identify in the field by its opaque nature (unlike translucent carnelian), conchoidal fracture, and inability to be scratched by a steel knife. Commonly found in riverbeds, glacial deposits, or near volcanic regions. Proving ground: Western USA (Oregon, Idaho), India, and Brazil.