sedimentary
Green Chert (Jasper)
Cryptocrystalline Quartz (SiO2)
Hardness: 6.5-7 (Mohs); Color: Dark green with hints of brown; Luster: Waxy to dull; Crystal structure: Trigonal (microscopic); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7. Highly durable and opaque.
- Hardness
- 6
- Color
- Dark green with hints of brown
- Luster
- Waxy to dull
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Dark green with hints of brown; Luster: Waxy to dull; Crystal structure: Trigonal (microscopic); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7. Highly durable and opaque.
Formation & geological history
Formed by the accumulation of silica-rich organic remains or chemical precipitation in marine environments. Often found as nodules or layers within sedimentary rocks like limestone or dolomite, dating from various geological eras.
Uses & applications
Historically used for making stone tools due to its sharp fracture; currently used for lapidary work, jewelry (tumbled stones), and decorative landscape materials.
Geological facts
Green chert is often specifically called green jasper when used in jewelry. In ancient times, it was used to create spearheads and arrowheads because it breaks with incredibly sharp edges.
Field identification & locations
Identify by its characteristic conchoidal (shell-like) fracture patterns and high hardness - it will scratch glass. Commonly found in riverbeds, coastal areas, and limestone outcrops globally.
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