The Volcanic Sedimentary Complex of the Iberian Pyrite Belt is dominated by mudstone units and comprises felsic lavas/domes and pyroclastic units that define lava-cryptodome-pumice cone volcanoes. Sediment-matrix igneous breccias may outline the contacts of volcanic units, occur within them, or lie laterally to the volcanic centres. These breccias can form by several processes, each with its genetic implications, having nevertheless very similar final aspect. We have distinguished and characterized several sediment-matrix breccia types. The most abundant types are sediment-infill volcanic breccia and peperite; however other types of sediment-matrix breccia were also identified. The correct identification of these breccias is crucial to reconstruct the volcanic centres and to define the stratigraphy, which in mineralized volcanic provinces is a major issue both for metallogenic and mineral exploration models
