sedimentary

Chert (specifically Red Chert/Jasper)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale; Color: Reddish-brown with translucent areas; Luster: Waxy to vitreous; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture).

Hardness: 6
Color: Reddish-brown with translucent areas
Luster: Waxy to vitreous

Identified April 9, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Reddish-brown with translucent areas; Luster: Waxy to vitreous; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture).

Formation & geological history

Formed primarily from the accumulation of silica-rich microfossils like radiolaria or diatoms on the seafloor, later undergoing lithification. Red hues indicate iron oxide inclusions.

Uses & applications

Historically used for stone tools and arrowheads due to its sharp edges; modernly used as a decorative stone, in jewelry (when polished), and as road ballast.

Geological facts

Chert is one of the most durable sedimentary rocks and was among the first materials used by prehistoric humans to create fire and weaponry.

Field identification & locations

Identify by its conchoidal (shell-like) fracture, waxy surface, and extreme hardness (it will scratch glass). Commonly found in sedimentary basins or as nodules in limestone.