Breccia

Physical Properties

Hardness: 6-7 (if silica-cemented); Color: Variegated browns, grays, and tans with white or cream cement; Luster: Dull to earthy; Structure: Clastic with angular fragments over 2mm; Cleavage: None.

Formation & Geological History

Formed through the accumulation of angular debris from tectonic activity (fault breccia), landslides, or talus slopes where fragments are cemented together before becoming rounded by water transport. Occurs in various geological eras.

Uses & Applications

Primarily used as an ornamental stone in architecture, flooring, and landscaping. High-quality specimens with attractive colors are used for decorative interior tiles and sculpture.

Geological Facts

Unlike conglomerate rocks which have rounded clasts, breccia is defined by its sharp, angular fragments, indicating that the source material did not travel far before being buried and lithified.

Field Identification & Locations

Identify by looking for angular, broken fragments of older rocks trapped within a fine-grained matrix or cement. Common in fault zones and at the base of steep cliffs. Collectors look for high contrast between fragments and matrix.

Identified on: 5/2/2026

Mode: Standard