Hydrothermal mineralization is usually structurally controlled so it is important to understand the role of faulting and fracturing in enhancing rock permeability and facilitating fluid flow and mass transfer. This is the main theme of this interdisciplinary volume and the papers included are intended to provide an overview of current ideas at the interfaces of structural geology, fluid flow and mineralization research. The volume includes some speculative but provocative ideas which should stimulate a re-examination of existing concepts regarding fluid flow in fracture systems and the genesis of hydrothermal mineral deposits. It also highlights recent advances which show the importance of the development of fracture connectivity in focusing fluid flow. The volume concludes with a thematic set of papers presenting new research results on the genesis of the world famous Carboniferous base metal deposits of Ireland. This volume is intended for geoscientists studying the flow of fluids through fault, vein and fracture systems or the genesis of mineral deposits and will be of interest principally to those involved in the minerals industry and in academia.