sedimentary

Green Chert (Jasper)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 Mohs; Color: Olive green to muddy green; Luster: Waxy to dull; Crystal structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7

Hardness: 6
Color: Olive green to muddy green
Luster: Waxy to dull

Identified July 21, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Olive green to muddy green; Luster: Waxy to dull; Crystal structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7

Formation & geological history

Formed through the accumulation of silica-rich microfossils (like radiolarians) or chemical precipitation from silica-rich fluids in deep-sea or hydrothermal environments. These specimens likely originated in a marine sedimentary sequence.

Uses & applications

Primarily used for lapidary work, cabochons, and landscaping. Historically used for making stone tools (arrowheads, scrapers) due to its sharp conchoidal edges.

Geological facts

Green chert often gets its color from chlorite or iron inclusions. It is essentially the same material as flint or jasper, distinguished mainly by its color and opacity.

Field identification & locations

Identify in the field by its smooth, shell-like fracture (conchoidal), waxy luster, and its ability to scratch glass. Found frequently in riverbeds or coastal areas near tectonic uplift zones like the California Coast Ranges.