sedimentary

Banded Chert / Jasper

Silicon Dioxide (SiO2)

Hardness 6.5-7 Mohs. Displays distinct horizontal banding with reddish-brown, tan, and cream layers. Dull to sub-vitreous or waxy luster, conchoidal to uneven fracture, opaque to slightly translucent on thin edges.

Identified July 25, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from the microcrystalline precipitation of silica, often in ancient marine or lacustrine environments where silica-rich fluids deposited fine layers of microcrystalline quartz mixed with iron oxide impurities over vast geological timescales.

Uses & applications

Historically used for stone tools like arrowheads due to its sharp conchoidal fracture. Today it is popular among lapidary artists for cabochons, polished slabs, decorative carvings, and rock collections.

Geological facts

Banded cherts and jaspers are among the oldest rocks preserved on Earth, with some precambrian iron formations containing banded chert dating back over 3 billion years, preserving ancient microbial life traces.

Field identification & locations

Identified by its high hardness (scratches glass), distinct sedimentary layering, and microcrystalline silica structure. Commonly found in riverbeds, glacial deposits, and sedimentary rock formations worldwide.