sedimentary

Green Chert

Microcrystalline Quartz (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Dull olive green; Luster: Waxy to vitreous; Crystal Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

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

Identified July 9, 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: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed in marine environments from the accumulation of silica-rich organic remains like radiolarians or sponges, which chemically precipitate or replace existing carbonate sediment. Often associated with volcanic activity or deep-sea hydrothermal vents.

Uses & applications

Used historically for stone tools due to its sharp edges; modern uses include decorative landscaping, road construction aggregate, and lapidary for polished river stones.

Geological facts

Green chert often gets its color from trace amounts of ferrous iron or chlorite. It was highly prized by indigenous cultures for making scrapers and projectile points because of its predictable fracture patterns.

Field identification & locations

Identify by its characteristic conchoidal (shell-like) fracture, extreme hardness (will scratch glass), and waxy feel. Commonly found in riverbeds, coastal cliffs, or as nodules within limestone formations.