sedimentary

Chert (Yellow Jasper)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale; Color: Yellowish-brown to tan; Luster: Dull to waxy; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7.

Hardness: 6
Color: Yellowish-brown to tan
Luster: Dull to waxy

Identified May 7, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Yellowish-brown to tan; Luster: Dull to waxy; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7.

Formation & geological history

Formed via the accumulation of silica-rich organic remains or through the chemical precipitation of silica in sedimentary environments. Its age can range from Precambrian to recent geological eras.

Uses & applications

Used historically for stone tools due to its sharp edges when broken. Frequently used today for decorative landscaping, lapidary work, and as a semi-precious gemstone in jewelry when it is high-quality jasper.

Geological facts

Yellow jasper is a variety of chert colored by iron inclusions (goethite). It has been used by humans for hundreds of thousands of years to create arrowheads and scrapers because of its predictable fracture pattern.

Field identification & locations

Identify in the field by its smooth, waxy texture and distinctive shell-like (conchoidal) fracture pattern when chipped. It is commonly found in riverbeds, desert pavements, and as nodules in limestone or chalk deposits.