sedimentary

Chert (Yellow or Brown Jasper)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

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

Hardness: 6
Color: Tan, brown, ochre
Luster: Waxy to dull

Identified April 8, 2026More sedimentary →

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Physical properties

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

Formation & geological history

Formed through the accumulation of silica-rich organic remains (like diatoms or radiolarians) or the chemical replacement of limestone/dolomite. It is found in deposits ranging from Precambrian to Cenozoic eras.

Uses & applications

Historically used for stone tools (flintknapping). Modernly used in geological collections, landscaping, and occasionally as a low-cost gemstone for cabochons.

Geological facts

Jasper is a variety of chert that gets its opaque color from high concentrations of iron oxides. It is so tough that it was one of the primary materials used by prehistoric humans to make arrowheads and scrapers.

Field identification & locations

Identify in the field by its waxy texture, smooth rounded edges (if river-worn), and conchoidal (shell-like) fracture patterns if chipped. It will easily scratch glass and steel.