sedimentary

Green Chert (Jasper / Flint)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Sage green, greyish-green to bluish-green; Luster: Waxy to vitreous; Fracture: Pronounced conchoidal fracture with sharp edges; Structure: Microcrystalline/cryptocrystalline quartz.

Hardness: 6
Color: Sage green, greyish-green to bluish-green
Luster: Waxy to vitreous

Identified July 25, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of silica-rich biogenic ooze (microscopic organisms like radiolarians and diatoms) on the ocean floor, or via chemical precipitation of silica in sedimentary rock layers over millions of years.

Uses & applications

Historically used for stone tools, arrowheads, and fire-starting (flint). Modern uses include lapidary arts, decorative rock landscaping, tumbled gemstone collecting, and crushed aggregate.

Geological facts

Green chert gets its distinctive color from inclusions of iron-bearing silicate minerals such as celadonite, chlorite, or micro-inclusions of green clay during its crystallization process.

Field identification & locations

Easily identified by its high hardness (scratches glass), waxy appearance, smooth conchoidal fracturing, and sharp edges. Widely found in marine sedimentary formations worldwide, particularly in riverbeds, gravel deposits, and limestone nodule beds.

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