sedimentary
Chert (Jasper)
Microcrystalline Quartz (SiO2) with Iron Oxide inclusions
Hardness: 6.5-7 on Mohs scale; Color: Reddish-brown to orange-brown; Luster: Waxy to dull; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91
- Hardness
- 6
- Color
- Reddish-brown to orange-brown
- Luster
- Waxy to dull
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Reddish-brown to orange-brown; Luster: Waxy to dull; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91
Formation & geological history
Formed by the precipitation of silica from groundwater or as a replacement of organic material such as limestone. The red/orange hue indicates high iron oxide content. It can range from Precambrian to recent geological ages.
Uses & applications
Used historically for stone tools (arrowheads), modern lapidary work (jewelry, beads), and as heavy-duty landscaping material.
Geological facts
Red jasper was highly prized in antiquity and mentioned in many historical texts, including the Bible and Greek mythology, as a stone of protection and endurance.
Field identification & locations
Identify by its conchoidal (shell-like) fracture, intense hardness (cannot be scratched by a steel knife), and opaque waxy appearance. Commonly found in river beds or sedimentary outcrops.
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