sedimentary
Jasper (Iron-rich Chert)
Silicon Dioxide (SiO2) with iron oxide impurities
Hardness: 6.5-7 on Mohs scale; Color: Reddish-brown, earthy ochre, or rust; Luster: Dull to waxy; Structure: Microcrystalline/cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91
- Hardness
- 6
- Color
- Reddish-brown, earthy ochre, or rust
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Reddish-brown, earthy ochre, or rust; Luster: Dull to waxy; Structure: Microcrystalline/cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91
Formation & geological history
Formed through the process of silica-rich water permeating sedimentary deposits or volcanic ash. The red-brown color originates from iron oxide (hematite or goethite) inclusions. It often exists as nodules or in banded layers in ancient seafloor environments.
Uses & applications
Used primarily in lapidary arts for jewelry, beads, and cabochons. Historically used for making tools due to its conchoidal fracture which produces sharp edges, and for decorative architectural stone.
Geological facts
Jasper was a favorite gem in the ancient world; its name can be traced back in Arabic, Persian, Hebrew, Assyrian, Greek, and Latin. It is often referred to as the 'supreme nurturer' in metaphysical circles.
Field identification & locations
Identify in the field by its opacity (even thin slivers won't let light through), its smooth, waxy feel when polished by water, and its inability to be scratched by a steel knife. Commonly found in riverbeds and gravel pits in areas such as Lake Superior, the Pacific Northwest, and India.
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