sedimentary

Chert (Green variety)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 Mohs; Color: Pale green to olive with tan cortex; Luster: Waxy to vitreous; Crystal Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7

Hardness: 6
Color: Pale green to olive with tan cortex
Luster: Waxy to vitreous

Identified June 6, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Pale green to olive with tan cortex; Luster: Waxy to vitreous; Crystal Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7

Formation & geological history

Formed through the accumulation of silica-rich organic remains or chemical precipitation in marine or groundwater environments. Often occurs as nodules or layers within limestone or shale.

Uses & applications

Used historically for making sharp tools and arrowheads due to its conchoidal fracture. Today used in construction aggregate, as decorative stones, or for lapidary tumbling.

Geological facts

Chert is a broad term that includes varieties like flint and jasper. It is known for its extreme durability and ability to maintain a sharp edge, which was vital to Stone Age technologies.

Field identification & locations

Look for a smooth, waxy surface and shell-like (conchoidal) fractures. Often found in creek beds or eroding out of limestone cliffs. It will easily scratch glass.