BRECCIA
Breccia
is an uncommon, coarse-grained, siliciclastic sedimentary rock. Breccias
form in many ways (sedimentary breccias, volcanic breccias, tectonic
breccias/fault breccias, collapse breccias, boiling breccias, hydrothermal
breccias, seismite breccias, injectite breccias, etc.), but they all have the
same general appearance. Sedimentary breccias contain a mix of large
& small grains. The large grains (gravel - pebbles or cobbles or
boulders) are angular to subangular in shape, and they are surrounded by a
finer-grained matrix, usually sand or mud.
Breccia
Jasper Breccia (cut & polished surface) - this attractive
breccia contains abundant reddish- and yellowish-colored chert fragments
surrounded by a very dark brown matrix of finer-grained material. I’m not sure of the provenance of this rock,
but I suspect it comes from Arkansas or Oklahoma (corrections or verifications
are welcome).