Breccia is primarily a clastic sedimentary rock composed of large, angular fragments or clasts that are greater than 2 millimeters in size. The key characteristic that distinguishes breccia from conglomerate is the shape of the fragments: breccia's clasts are sharp and angular, whereas conglomerate clasts are rounded. This angularity indicates that breccia fragments have not been transported far from their source, reflecting rapid deposition close to where the rock fragments were produced. The spaces between the fragments in breccia are typically filled with a finer-grained matrix or mineral cement that binds the rock together. Breccia can form through various mechanisms and occurs in different types, including sedimentary breccia (formed by sedimentary processes such as rock-falls or debris flows), volcanic breccia (an extrusive igneous rock made of angular volcanic fragments), impact breccia (formed by meteorite impacts), and fault (tectonic) breccia (formed by grinding and fracturing along fault zones). The composition of breccia varies depending on the rock fragments it contains and can include quartz, feldspar, lithics, or various rock fragment types. Overall, the defining type of rock breccia falls under is clastic sedimentary rock, though it can be associated with igneous or tectonic origins as well based on its formation process.