sedimentary

Chert (Yellow/Tan Jasper)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale; Color: Tan, yellow, and brown banding/mottling; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7

Hardness: 6
Color: Tan, yellow, and brown banding/mottling
Luster: Waxy to vitreous

Identified June 28, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed via the accumulation of siliceous remains of organisms or precipitation from silica-rich fluids in sedimentary environments. Often found as nodules in limestone or as stream-tumbled pebbles.

Uses & applications

Used historically for stone tools and weapons due to its sharp edges; currently used in jewelry (as jasper), rock tumbling for collectors, and as decorative aggregate.

Geological facts

Chert and Jasper were among the most important materials for prehistoric humans to create arrowheads and scrapers. The yellow color is usually caused by the presence of goethite or other iron oxides.

Field identification & locations

Identify in the field by its smooth, waxy texture and distinctive conchoidal (shell-like) fracture patterns. Frequently found in riverbeds, gravel pits, and coastal areas.