sedimentary

Brown Jasper (Chert)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 Mohs; Color: Chocolate brown with yellow/tan inclusions; Luster: Waxy to dull; Crystal Structure: Microcrystalline; Fracture: conchoidal; Specific Gravity: 2.6-2.9.

Hardness: 6
Color: Chocolate brown with yellow/tan inclusions
Luster: Waxy to dull

Identified June 12, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Chocolate brown with yellow/tan inclusions; Luster: Waxy to dull; Crystal Structure: Microcrystalline; Fracture: conchoidal; Specific Gravity: 2.6-2.9.

Formation & geological history

Formed from the accumulation of silica-rich microfossils or chemical precipitation in sedimentary basins. The brown color is derived from iron oxide (goethite) inclusions. Many specimens are river-worn, giving them a smooth, rounded appearance.

Uses & applications

Used primarily in lapidary work, jewelry making (cabochons), as pocket stones for meditation, and as decorative gravel.

Geological facts

Jasper is a variety of chalcedony that is opaque due to high mineral impurities. It has been used since antiquity for seals and ornamentation. This specific specimen appears to be a water-worn river cobble.

Field identification & locations

Identify in the field by its hardness (cannot be scratched by a steel knife), smooth waxy texture, and opaque nature. Often found in riverbeds or coastal areas where erosion has polished the stones naturally.