sedimentary

Jasper

Jasper (Silicon Dioxide, SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Tan, brown, orange, and yellow (iron-stained); Luster: Dull to waxy when dry, vitreous when wet; Structure: Microcrystalline/Cryptocrystalline quartz; Cleavage: None/Conchoidal fracture; Specific gravity: 2.58-2.91

Hardness: 6
Color: Tan, brown, orange, and yellow (iron-stained)
Luster: Dull to waxy when dry, vitreous when wet

Identified June 24, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the infiltration of silica-rich fluids into sedimentary rock or volcanic ash, followed by dehydration and lithification. Often found as water-worn cobbles in riverbeds and coastal regions.

Uses & applications

Used primarily in lapidary arts for decorative stones, cabochon jewelry, and as aquarium or landscaping gravel. Historically used for making stone tools due to its conchoidal fracture.

Geological facts

Jasper is an opaque variety of chalcedony. The wide variety of patterns and colors are caused by impurities like iron oxides (rust) and clay minerals trapped during formation. No two jasper stones are exactly alike.

Field identification & locations

Identify in the field by its hardness (cannot be scratched by a steel knife) and its smooth, waxy texture compared to surrounding rocks. Often found along stream beds or beaches where water erosion has rounded the material.