sedimentary

Chert (Jasper influence)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale. Color: Brownish-red to tan with earthy mottling. Luster: Dull to waxy. Crystal structure: Trigonal (microcrystalline). Cleavage: None (conchoidal fracture). Specific gravity: 2.6 - 2.65.

Hardness: 6
Color: Brownish-red to tan with earthy mottling
Luster: Dull to waxy

Identified April 11, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of silica-rich organic debris or chemical precipitation in marine or groundwater environments. This specimen appears weathered and stained with iron oxides (hematite/limonite).

Uses & applications

Historically used for stone tools/arrowheads. Modernly used in landscaping, as tumbling rough, or for decorative lapidary work.

Geological facts

Chert has been used by humans for hundreds of thousands of years due to its ability to maintains a sharp edge when fractured. Reddish varieties are often called Jasper.

Field identification & locations

Identify in the field by its hardness (it will scratch glass) and its smooth, shell-like (conchoidal) fracture surfaces. Commonly found in riverbeds and limestone formations.