sedimentary

Green Chert (Jasper)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale; Color: Dull olive green; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7

Hardness: 6
Color: Dull olive green
Luster: Waxy to vitreous

Identified April 2, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Dull olive green; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7

Formation & geological history

Formed through the accumulation of silica-rich organic remains (like diatoms or radiolarians) or by chemical precipitation in marine environments. Often found in nodules within limestone or as bedded deposits.

Uses & applications

Used historically for stone tools and arrowheads due to its sharp conchoidal fracture. Today used as a decorative stone, in lapidary work (cabochons), and as a collector's specimen.

Geological facts

Green chert is sometimes called 'Green Jasper' in the gemstone trade. Because of its extreme hardness and durability, it has been used by humans for millions of years to create cutting tools.

Field identification & locations

Identify in the field by its waxy luster, smoothness, and distinct shell-like (conchoidal) curves where broken. It cannot be easily scratched by a steel knife. Common in sedimentary basins worldwide.