sedimentary

Yellow Jasper (Chert variant)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Creamy white to mustard yellow; Luster: Waxy to dull; Crystal structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91

Hardness: 6
Color: Creamy white to mustard yellow
Luster: Waxy to dull

Identified March 25, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of silica-rich microfossils or precipitation from silica-rich hydrothermal fluids in sedimentary environments. Its age can range from Precambrian to relatively recent Cenozoic deposits.

Uses & applications

Commonly used in lapidary work for cabochons, beads, and tumbled stones. Historically used for making tools and arrowheads due to its sharp conchoidal fracture.

Geological facts

Jasper is an opaque variety of chalcedony. The yellow coloring usually comes from iron inclusions (goethite). It has been a popular gemstone since antiquity and was referenced in many ancient cultures as a protective stone.

Field identification & locations

Identify in the field by its hardness (cannot be scratched by a steel knife), smooth waxy feel, and characteristic curved (conchoidal) fractures when chipped. Frequently found in riverbeds and coastal areas as water-worn pebbles.

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