Porphyry-style Cu-Au/Mo deposits are among the most sought after targets for both base and precious metal exploration in the world today. Of particular interest are the "super porphyry" copper and/or gold deposits, because of their size, grade and ability to support large scale, long life, profitable operations.

The term "super porphyry" is interpreted loosely in this publication, relating in general to the largest deposits in any established porphyry province. For a discussion of the accepted terminology and size classification of large porphyry-style deposits, see the introduction section of Richards, (2005) in this publication.

This preface presents the background to this book, the second volume of the "Hydrothermal Iron Oxide Copper-Gold & Related Deposits - A Global Perspective" series, and briefly discusses the rationale for inviting the papers it contains, their format and what it is hoped the volume will achieve. It also offers some observations on the unifying characteristics of the iron oxide copper-gold family of deposits and what they may represent in a broader context.

The "hydrothermal iron-oxide copper-gold" (IOCG) family and related deposits continue to attract keen interest, both as the subject of academic research and as arguably the most sought after mineral exploration target in the world today.

Following the discovery of the giant Olympic Dam ore deposit in 1975, a realisation developed that there was an important class of mineral deposits not previously appreciated. It became apparent that this class, the Iron Oxide Copper-Gold deposits, included not only Olympic Dam, but also a number of other known deposits. It also became apparent that this was a class that could produce large, high grade prizes, of the order of 0.25 to 1 billion tonnes of around +1% Cu and 0.5 g/t Au. As a consequence this class has been one of the major targets of the exploration industry over the last decade, resulting in the discovery of further giant orebodies in Australia such as Ernest Henry, and Candelaria, Salobo, Sossego and others in South America.

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.