sedimentary

Chert (Jasper)

Microcrystalline Quartz (SiO2)

Hardness: 6.5-7 (Mohs scale), Color: Red, brown, and pinkish-tan with darker bands, Luster: Waxy to dull, Crystal Structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture)

Hardness: 6

Identified June 11, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs scale), Color: Red, brown, and pinkish-tan with darker bands, Luster: Waxy to dull, Crystal Structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture)

Formation & geological history

Formed via the accumulation of silica-rich marine organisms or chemical precipitation from hydrothermal fluids in sedimentary basins. The reddish hues suggest iron oxide inclusions.

Uses & applications

Historically used for stone tools due to its sharp edges when fractured. Modernly used in geological collections, landscaping, and occasionally lapidary work.

Geological facts

Chert and Jasper are varieties of microcrystalline quartz. This specific specimen shows banded patterns common in sedimentary deposits where different mineral levels fluctuate during deposition.

Field identification & locations

Identified in the field by its waxy luster, hardness (it can scratch glass), and its characteristic conchoidal (shell-like) fracture pattern. Commonly found in riverbeds or within limestone formations.