sedimentary
Polygenetic Breccia
Clastic Breccia (containing lithic fragments in a fine-grained matrix)
Hardness: 6-7 (individual clasts like quartz), variable for matrix; Color: Black/dark grey matrix with tan, red, and grey clasts; Luster: Dull/Earthly; Structure: Clastic, coarse-grained with angular to sub-angular fragments; Cleavage: None/Irregular fracture.
- Hardness
- 6-7 (individual clasts like quartz), variable for matrix
- Color
- Black/dark grey matrix with tan, red, and grey clasts
- Luster
- Dull/Earthly
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6-7 (individual clasts like quartz), variable for matrix; Color: Black/dark grey matrix with tan, red, and grey clasts; Luster: Dull/Earthly; Structure: Clastic, coarse-grained with angular to sub-angular fragments; Cleavage: None/Irregular fracture.
Formation & geological history
Formed through the mechanical breakage of various pre-existing rocks by tectonic activity, landslides, or impact events, followed by cementation within a fine-grained matrix. Often ancient, dating from hundreds of millions to billions of years depending on the specific formation site.
Uses & applications
Used primarily as decorative stone, construction aggregate, or as a geological indicator for fault zones or ancient impact sites; common in educational collections.
Geological facts
Breccia is often confused with conglomerate; the key difference is that breccia contains sharp, angular fragments while conglomerate has rounded ones. It typically forms very close to the source of the breakage.
Field identification & locations
Identify in the field by looking for unsorted, sharp-edged rock fragments embedded in a finer material. Often found along fault lines, base of cliffs (talus), or impact craters. Look for varied colors in the 'chunks' (clasts) compared to the 'glue' (matrix).
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone (Quartz-rich)
Arenite (SiO2)
sedimentary
Sandstone (with man-made markings)
Arenite (composed primarily of Quartz, SiO2)
sedimentary