Geologists have been very generous in their use of the word “breccia.” It is common to hear the term used when referring to a rock or rock debris made up of angular fragments. Although it is mainly used for rocks of sedimentary origin, it can be used for other types of rocks. A few more uses of the word are given below.

Collapse Breccia: Broken rock that originates from a cavern or magma chamber collapse.

Fault Breccia or Tectonic Breccia: Broken rock found in the contact area between two fault blocks and produced by movement of the fault.

Flow Breccia: A lava texture produced when the crust of a lava flow is broken and jumbled during movement.

Fold Breccia: A breccia formed by the folding and breakage of thin, brittle rock layers which are interlayered with incompetent, ductile layers.

Igneous Breccia or Volcanic Breccia: A term used for a rock composed of angular fragments of igneous rocks. “Flow breccia” and “pyroclastic breccia” could be called “igneous breccia.”

Impact Breccia: A deposit of angular rock debris produced by the impact of an asteroid or other cosmic body. See an article about “impactites.”

Monomict Breccia: A breccia whose clasts are composed of a single rock type, possibly all from a single rock unit.

Polymict Breccia: A breccia whose clasts are composed of many different rock types.

Pyroclastic Breccia: A term used for a deposit of igneous rock debris that was ejected by a volcanic blast or pyroclastic flow.

When you hear the word “breccia” used in reference to a rock or rock material, it is fairly safe to assume that it means angular-shaped pieces.