sedimentary

Breccia

Breccia (Sedimentary Clastic Rock)

Hardness: variable depending on clasts and cement (typically 3-7 Mohs); Color: mottled, white to cream angular clasts in a dark gray to black matrix; Luster: earthy to dull; Texture: coarse-grained, clastic with sharply angular fragments.

Hardness: variable depending on clasts and cement (typically 3-7 Mohs)
Luster: earthy to dull

Identified July 23, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from the lithification of angular mineral or rock fragments bound together by a finer-grained matrix or mineral cement. Typically originates in fault zones, talus slopes, alluvial fans, or impact events where fragments do not travel far enough to become rounded.

Uses & applications

Used primarily as decorative stone, facing stone for buildings, landscaping material, aggregate in construction, and as an educational geological sample.

Geological facts

Unlike conglomerates, which feature rounded pebbles smoothed by water or wind transport, breccia contains sharp, angular fragments indicating minimal transport distance before burial and cementation.

Field identification & locations

Easily identified in the field by its distinct 'mosaic' appearance featuring visible, angular fragments cemented in a finer matrix. Commonly found in tectonic fault zones, ancient mountainous alluvial fans, and karst collapse zones.