sedimentary

Yellow Chert (Jasper)

Chalcedony (SiO2) with iron oxide inclusions

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale; Color: mustard yellow to tan; Luster: waxy to dull; Crystal structure: cryptocrystalline; Cleavage: none, exhibits conchoidal fracture; Specific gravity: approx 2.6

Hardness: 6
Color: mustard yellow to tan
Luster: waxy to dull

Identified March 2, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: mustard yellow to tan; Luster: waxy to dull; Crystal structure: cryptocrystalline; Cleavage: none, exhibits conchoidal fracture; Specific gravity: approx 2.6

Formation & geological history

Formed from the precipitation of silica-rich fluids in sedimentary environments or through the replacement of limestone. This specimen likely originates from Paleozoic to Mesozoic era deposits.

Uses & applications

Historically used for stone tools and arrowheads; currently used in jewelry (cabochons), as landscaping stone, and for specimen collecting.

Geological facts

Chert and Jasper are often used interchangeably when the color is opaque; the yellow tint is specifically caused by the presence of goethite or limonite. It is one of the most durable sedimentary rocks.

Field identification & locations

Identify in the field by its smooth, waxy feel and the way it breaks into curved, glass-like shards (conchoidal fracture). Frequently found in riverbeds, gravel pits, and eroding out of limestone outcrops.