sedimentary

Yellow Chert or Jasper

Microcrystalline Quartz (SiO2) with iron oxide inclusions

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale; Color: Dull yellow to mustard; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.65.

Hardness: 6
Color: Dull yellow to mustard
Luster: Waxy to dull

Identified May 14, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Dull yellow to mustard; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.65.

Formation & geological history

Formed via the accumulation of silica-rich fluids in sedimentary environments or through the replacement of limestone. This specimen shows significant rounding from water erosion (fluvial or beach action).

Uses & applications

Used historically for stone tools due to sharp edges when fractured; modernly used for decorative landscaping, jewelry (if high quality), and as an abrasive.

Geological facts

Chert and jasper are among the oldest materials used by early humans for tools because of their hardness and predictable fracture patterns. Yellow hues are typically caused by goethite or limonite.

Field identification & locations

Identify in the field by its smooth, waxy surface when wet and its ability to scratch glass. Found globally in riverbeds, glacial tills, and coastal regions.