Abstract - Hydrothermal copper & gold deposits associated with felsic intrusives, particularly porphyry related and epithermal ores, are found in a series of extensive, narrow, linear metallogenic provinces throughout the world. These are predominantly associated with the great Mesozoic to Cainozoic orogenic belts. Major deposits however, are also found within Palaeozoic orogens, while a few are known from the Precambrian. The style and setting of these deposits is variable and diverse, although many common features emerge from a global comparison.

Analyses of exploration and mining case studies as well as magmatic arc geothermal systems have facilitated an understanding of the implications to explorationists of the anatomy of porphyry related Au-Cu-Mo-Ag mineralising systems. Deeply eroded magmatic source rocks tend to host sub economic mineralisation, which may become focused in the highly prospective in overlying apophyses to spine-like polyphasal intrusions. Buried targets may be identified by analyses of zoned alteration and mineralisation developed by complex overprinting relationships. Mineralised fluids may exit from the magmatic source migrating to higher crustal levels to form epithermal deposits. High sulphidation epithermal Au + Cu + Ag deposits display characteristic alteration and mineralisation zonation which aids target generation and in some instances evolve to host marginal and overprinting lower sulphidation ores which display improved metallurgy and metal grades. Low sulphidation epithermal Au-Ag deposits are categorised as a number of styles, linked on an overall anatomy, which display considerable variation in metal grade, size, form and metallurgy, typically governed by setting and crustal level of formation, as well as controls to vein formation such as: host rock competency, structure, and mechanism of Au deposition. All these controls and zonation pattern vectors provide valuable tools to explorationists in the search for hidden ores.