sedimentary

Chert (Yellow Jasper variant)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5–7 on Mohs scale; Color: Dull yellow to tan; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6–2.7

Hardness: 6
Color: Dull yellow to tan
Luster: Waxy to vitreous

Identified March 22, 2026More sedimentary →

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Physical properties

Hardness: 6.5–7 on Mohs scale; Color: Dull yellow to tan; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6–2.7

Formation & geological history

Formed through the accumulation of silica-rich organic remains or chemical precipitation in marine or groundwater environments. This specimen is a water-worn river pebble, likely shaped over thousands of years.

Uses & applications

Historically used for stone tools/arrowheads. Modern uses include jewelry (if polished), landscaping gravel, and as a raw material for silicon production.

Geological facts

Yellow chert gets its color from iron oxide (limonite) inclusions. Due to its fracture patterns, it was one of the most important materials for early human technology, categorized as 'lithic' archaeological material.

Field identification & locations

Identify in the field by its smooth, 'heart-shaped' or rounded water-worn texture and its inability to be scratched by a steel pocket knife. Found commonly in riverbeds and glacial tills.