sedimentary

Jasper

Silicon Dioxide (SiO2) with impurities

Hardness: 6.5-7 on Mohs scale; Color: Reddish-brown with light streaks; Luster: Dull to waxy; Crystal Structure: Microcrystalline/Cryptocrystalline; Cleavage: None (Conchoidal fracture); Specific Gravity: 2.58-2.91

Hardness: 6
Color: Reddish-brown with light streaks
Luster: Dull to waxy

Identified July 2, 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 during diagenesis. The brownish-red color is typically due to iron oxide (hematite) inclusions.

Uses & applications

Used primarily as decorative gemstones, in jewelry (cabochons), as polished pocket stones, and historically for tools due to its conchoidal fracture.

Geological facts

Jasper has been used by humans for thousands of years; it was a favorite gem in the ancient world, mentioned in the Bible and used in Minoan seals. Its name is derived from the Greek word 'iaspis', meaning 'spotted stone'.

Field identification & locations

Look for a smooth, opaque stone that cannot be scratched by a steel knife. It is commonly found on beaches or in stream beds as water-worn pebbles. Common in coastal areas and volcanic regions worldwide.