sedimentary

Green Chert

Microcrystalline Quartz (SiO2)

Hardness: 7 on Mohs scale; Color: olive-green to dark grey-green; Luster: waxy to dull; Cleavage: none (conchoidal fracture); Specific gravity: ~2.65

Hardness: 7 on Mohs scale
Color: olive-green to dark grey-green
Luster: waxy to dull

Identified July 27, 2026More sedimentary →

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Physical properties

Hardness: 7 on Mohs scale; Color: olive-green to dark grey-green; Luster: waxy to dull; Cleavage: none (conchoidal fracture); Specific gravity: ~2.65

Formation & geological history

Formed through the accumulation and recrystallization of silica-rich biogenic sediments (like radiolarian tests) or chemical precipitation in marine environments.

Uses & applications

Historically used for stone tools, arrowheads, and spark-striking. Today used primarily in road aggregate, lapidary projects, and specimen collections.

Geological facts

Chert forms smoothly curved, sharp conchoidal fractures, making it one of the earliest materials humans used to manufacture cutting weapons and tools.

Field identification & locations

Identified in the field by its extreme hardness (scratches glass/steel easily), smooth conchoidal fracturing, and waxy luster. Common in bedded limestone and chalk formations worldwide.