sedimentary

Brecciated Chert with Quartz Veining

Microcrystalline Quartz (SiO2) Breccia

Hardness: 6.5-7 on Mohs scale; Color: Dark grey to brown matrix with white/cream chert and quartz veinlets; Luster: Waxy to vitreous; Structure: Cryptocrystalline to microcrystalline, brecciated texture; Fracture: Conchoidal to uneven.

Hardness: 6
Luster: Waxy to vitreous

Identified July 26, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in sedimentary marine or lacustrine environments where microcrystalline silica accumulated, became indurated, and was subsequently fractured by tectonic activity, allowing silica-rich fluids to fill the fractures and heal the rock into a breccia.

Uses & applications

Used primarily for lapidary arts, decorative rock collections, landscaping, and educational geology specimens.

Geological facts

Brecciated chert often records geological strain and fluid movement. The crisscrossing dark lines are filled micro-fractures (stockwork veining), illustrating hydraulic fracturing in rock formations.

Field identification & locations

Identified by its high hardness (scratches glass), waxy luster, angular brecciated fragments, and prominent cross-cutting quartz veinlets. Commonly found in ancient sedimentary basins, riverbeds, and gravel deposits worldwide.

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