sedimentary

Chert (Jasper)

Microcrystalline Quartz (SiO2)

Hardness: 6.5-7 (Mohs), Color: Reddish-brown to tan, Luster: Waxy to dull, Structure: Cryptocrystalline, Cleavage: None (Conchoidal fracture), Specific Gravity: 2.6-2.7

Hardness: 6

Identified May 24, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs), Color: Reddish-brown to tan, Luster: Waxy to dull, Structure: Cryptocrystalline, Cleavage: None (Conchoidal fracture), Specific Gravity: 2.6-2.7

Formation & geological history

Formed primarily through the chemical precipitation of silica-rich fluids within sedimentary rock layers or as volcanic deposits. It often replaces organic matter or carbonate minerals.

Uses & applications

Historically used for stone tools (arrowheads). Modernly used in lapidary work, jewelry, and as an abrasive or aggregate.

Geological facts

Red jasper gets its color from iron inclusions. It has been used for thousands of years as a gemstone and was considered a sacred stone of physical and spiritual protection in many ancient cultures.

Field identification & locations

Identified by its extreme hardness (scratches glass), smooth waxy texture, and shell-like (conchoidal) fracture pattern. Found globally in riverbeds, glacial tills, and sedimentary outcrops.