sedimentary

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 Mohs; Color: Brown, red, tan, and white; Luster: Dull to waxy; Structure: Microcrystalline (hidden crystals); Fracture: Conchoidal (shell-like curves); Opaque.

Hardness: 6
Color: Brown, red, tan, and white
Luster: Dull to waxy

Identified July 10, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Brown, red, tan, and white; Luster: Dull to waxy; Structure: Microcrystalline (hidden crystals); Fracture: Conchoidal (shell-like curves); Opaque.

Formation & geological history

Formed through the accumulation of silica-rich microfossils (like radiolarians or diatoms) or by chemical precipitation from hydrothermal fluids within limestone or volcanic environments.

Uses & applications

Historically used for stone tools and weapons due to its sharp edges; modernly used as a pocket stone, in jewelry (lapidary), and for landscaping.

Geological facts

Jasper is an impure variety of chert. The color variations in this specimen are likely caused by iron oxide (brown/red) and other mineral inclusions. It was one of the most important minerals for early humans to create survival tools.

Field identification & locations

Identify in the field by its hardness (will scratch glass), smooth waxy feel, and curved, glass-like fracture surfaces. Often found in riverbeds or as nodules in limestone.