What is the X in X-mas?
"rock of angular pieces," 1774, from Italian breccia, "marble of angular pieces," from a Germanic source akin to Old High German brecha "a breaking," from Proto-Germanic *brekan, from PIE *bhreg- "to break" (see fraction).
A rock composed of angular fragments embedded in a fine-grained matrix. Breccias form from explosive volcanic ejections, the compaction of talus, or plate tectonic processes. Breccias are different from conglomerates in that the fragments they contain are angular instead of rounded.