sedimentary

Breccia

Clastic Breccia

Hardness: variable (3-7 Mohs depending on clasts); Color: dark grey to black matrix with grey clasts; Luster: dull to earthy; Texture: clastic (coarse-grained, angular fragments); Cleavage: none.

Hardness: variable (3-7 Mohs depending on clasts)
Color: dark grey to black matrix with grey clasts
Luster: dull to earthy

Identified July 5, 2026More sedimentary →

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Physical properties

Hardness: variable (3-7 Mohs depending on clasts); Color: dark grey to black matrix with grey clasts; Luster: dull to earthy; Texture: clastic (coarse-grained, angular fragments); Cleavage: none.

Formation & geological history

Formed by the lithification of angular rock fragments or mineral debris. They are created through tectonic activity, landslides, or in alluvial fans where fragments have not traveled far enough to be rounded by water.

Uses & applications

Used primarily as road base, construction aggregate, and occasionally as architectural stone or for landscaping.

Geological facts

Breccia is distinguished from conglomerate by the angularity of its fragments. The word comes from the Italian for 'loose gravel' or 'stone fragments'.

Field identification & locations

Identified in the field by large, angular pieces (clasts) cemented together by a finer-grained matrix. Found near fault zones, at the base of cliffs, or in impact craters. Collectors look for unique color contrasts between fragments and matrix.