sedimentary
Jasper (specifically Yellow or Brown Jasper)
Silicon Dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 on Mohs scale; Color: Mustard yellow, brownish-yellow with darker bands; Luster: Vitreous to waxy; Crystal Structure: Microcrystalline (trigonal); Fracture: Conchoidal; Opaque.
- Hardness
- 6
- Color
- Mustard yellow, brownish-yellow with darker bands
- Luster
- Vitreous to waxy
Identified More sedimentary →
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Mustard yellow, brownish-yellow with darker bands; Luster: Vitreous to waxy; Crystal Structure: Microcrystalline (trigonal); Fracture: Conchoidal; Opaque.
Formation & geological history
Formed from the deposition of silica-rich fluids in sedimentary environments or volcanic ash beds. The yellow/brown coloring comes from high concentrations of goethite or limonite (iron oxides). Often found as water-worn pebbles in stream beds.
Uses & applications
Used primarily in lapidary arts for cabochons, beads, and decorative carvings. Historically used for seals and amulets. Also used as a common landscaping stone in tumbled form.
Geological facts
Jasper was a favorite gem in the ancient world; its name can be traced back in Arabic, Persian, Greek, and Latin. It is an impure variety of silica, usually containing up to 20% of foreign materials which determine its color and opacity.
Field identification & locations
Identify by its waxy luster when wet or polished, its smoothness, and its inability to be scratched by a steel knife. Common in riverbeds and coastal areas where volcanic and sedimentary rocks interact.
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