Here's why:

* Formation: Breccia forms from fragments of other rocks that have been broken down and cemented together. This process of fragmentation and cementation is a key characteristic of sedimentary rock formation.

* Composition: The fragments in breccia can be of any rock type, including igneous, metamorphic, or even other sedimentary rocks. This mix of different rock types is another hallmark of sedimentary rocks.

* Texture: The defining characteristic of breccia is its angular fragments. This angularity indicates that the fragments were not transported far before they were cemented together, unlike the rounded fragments found in conglomerates, another type of sedimentary rock.

So, while breccia may contain fragments of igneous or metamorphic rocks, it is ultimately classified as a sedimentary rock due to its formation process and the way its components are bound together.