sedimentary

Banded Chert / Jasper

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs); Color: Tan, brown, and yellow bands with waxy luster; Crystal Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 6
Color: Tan, brown, and yellow bands with waxy luster

Identified June 11, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Tan, brown, and yellow bands with waxy luster; Crystal Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed through the accumulation of silica-rich microfossils or precipitation from hydrothermal fluids in sedimentary basins or volcanic deposits. These silica layers harden over millions of years.

Uses & applications

Used historically for stone tools due to sharp edges; currently used for lapidary work, jewelry (cabs), and as a decorative landscaping stone.

Geological facts

Chert was one of the first materials humans used to make fire-starting strikers and tools. The bands represent different rhythmic depositional cycles or vary based on impurities like iron oxides.

Field identification & locations

Identify by its hardness (scratches glass), waxy feel, and smooth curved (conchoidal) breaks. Commonly found in riverbeds and limestone formations worldwide.