sedimentary

Chert (Jasper / Flint variant)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale. Color: Tan, yellowish-brown, brownish-red with distinct iron oxide banding. Luster: Waxy to dull/earthy. Crystal Structure: Microcrystalline/Cryptocrystalline. Cleavage: None (features smooth conchoidal to sub-conchoidal fracture). Specific Gravity: 2.58 - 2.64.

Hardness: 7 on Mohs scale
Luster: Waxy to dull/earthy

Identified July 25, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed via chemical precipitation of silica-rich fluids or biological diagenesis of silica-rich ooze (such as radiolarians or diatoms) in marine or freshwater environments. Secondary iron oxides create the distinctive reddish-brown banding.

Uses & applications

Historically used for making stone tools, arrowheads, and flintlock strikers due to its sharp conchoidal edges. Currently used in lapidary work, cabochon crafting, decorative landscaping, and stone collecting.

Geological facts

Chert and jasper have been used by humans for hundreds of thousands of years for toolmaking. When struck with steel or iron pyrite, chert generates sparks, making it one of humanity's earliest fire-starting materials.

Field identification & locations

Identified in the field by its hardness (scratches glass readily), smooth waxy feel, sharp edges on broken surfaces, and distinct color banding. Commonly found in limestone formations, stream beds, and gravel deposits worldwide.