sedimentary

Chert Breccia

Brecciated Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: Tan, brown, or white matrix with reddish-brown clasts; Luster: Waxy to dull/earthy; Texture: Clastic (angular fragments in a finer matrix); Cleavage: None (conchoidal fracture)

Hardness: 7 on Mohs scale
Color: Tan, brown, or white matrix with reddish-brown clasts
Luster: Waxy to dull/earthy

Identified March 26, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the mechanical breaking of chert beds followed by cementation with silica-rich fluids. Often associated with tectonic activity or karst collapse in Paleozoic to Mesozoic sedimentary basins.

Uses & applications

Used primarily as road base or aggregate in construction. High-quality specimens are occasionally used for landscaping or as lapidary rough for 'pudding stone' jewelry.

Geological facts

Breccia differs from conglomerate because its fragments are angular rather than rounded, indicating that the fragments did not travel far from their source before being cemented together.

Field identification & locations

Identify in the field by its hardness (will scratch glass) and the presence of sharp, angular rock fragments cemented in a solid mass. Commonly found in areas with limestone or dolomite bedrock.