The breccia units at the Songwe Hill / Mauze complex are located at, or close to, the contact between nepheline syenite and the surrounding country rock. They are small, the largest comprising an area no more than ~125 × 125 m, and occur at the top of small hills abutting the larger, steeper, Mauze mountain. Owing to sparse outcrop, many of the available samples are float. On the weathered surface, the rocks are buff-pink in colour, with local black Mn-oxide staining. Most samples are heavily altered and composed predominantly of clay minerals, after K-feldspar, and Fe- and Mn-oxide phases. Geological Magazine (2021) 158 (11): 2025-2041. https://doi.org/10.1017/S0016756821000601