sedimentary
Brown Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 (Mohs scale); Color: Earthy brown to reddish-brown; Luster: Waxy to dull; Crystal structure: Trigonal/Microcrystalline; Cleavage: None/Conchoidal fracture; Specific Gravity: 2.58-2.91
- Hardness
- 6
- Color
- Earthy brown to reddish-brown
- Luster
- Waxy to dull
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Earthy brown to reddish-brown; Luster: Waxy to dull; Crystal structure: Trigonal/Microcrystalline; Cleavage: None/Conchoidal fracture; Specific Gravity: 2.58-2.91
Formation & geological history
Formed when silica-rich fluids permeate porous sedimentary rocks or volcanic ash, with the brown color resulting from high concentrations of iron oxides (goethite or hematite). Often found as stream-rounded pebbles or nodules.
Uses & applications
Commonly used as a lapidary material for cabochons, beads, and decorative carvings. Historically used for making stone tools due to its conchoidal fracturing.
Geological facts
Jasper is an opaque variety of chalcedony. The name comes from the Greek word 'iaspis', meaning 'spotted stone'. Brown jasper is sometimes referred to as 'Egyptian Jasper' or 'Mud Jasper'.
Field identification & locations
Identify in the field by its opacity (will not let light through even at edges), waxy appearance when wet, and inability to be scratched by a steel knife. Found globally in riverbeds and mountainous regions.
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