sedimentary

Chert (Jasper)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 Mohs; Color: Red, white, and tan; Luster: Waxy to dull; Crystal structure: Cryptocrystalline (Trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.65

Hardness: 6
Color: Red, white, and tan
Luster: Waxy to dull

Identified June 15, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Red, white, and tan; Luster: Waxy to dull; Crystal structure: Cryptocrystalline (Trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.65

Formation & geological history

Formed through the accumulation of silica-rich microfossils (like radiolaria or diatoms) or by chemical precipitation from hydrothermal fluids in volcanic or sedimentary environments.

Uses & applications

Historically used for making stone tools (arrowheads); currently used in jewelry (cabochons), as an ornamental stone, and in lapidary arts.

Geological facts

Red jasper specifically gets its color from iron inclusions. It has been used for millennia by cultures globally for both practical tools and spiritual amulets.

Field identification & locations

Identify by its waxy luster, smoothness to the touch, and distinct shell-like (conchoidal) fractures. Common in riverbeds, desert regions, and areas with ancient seafloor activity.