The USGS has recently posted a very thorough Scientific Investigations Report about Cu-Porphyry deposits that is available for free download as a PDF. From the first few looks that I have taken inside it is most certainly a perfect start for any student or geologists who needs to know a bit more about Porphyries than you got to hear in the 15 minutes presentation in class. I am already loving it! Go HERE to visit the website and for download. The site gives a good content description that you can find below the front cover.
Front cover. Image source: USGS
This report contains a revised descriptive model of porphyry copper deposits (PCDs), the world’s largest source (about 60 percent) and resource (about 65 percent) of copper and a major source of molybdenum, gold and silver. Despite relatively low grades (average 0.44 percent copper in 2008), PCDs have significant economic and societal impacts due to their large size (commonly hundreds of millions to billions of metric tons), long mine lives (decades), and high production rates (billions of kilograms of copper per year). The revised model describes the geotectonic setting of PCDs, and provides extensive regional- to deposit-scale descriptions and illustrations of geological, geochemical, geophysical, and geoenvironmental characteristics. Current genetic theories are reviewed and evaluated, knowledge gaps are identified, and a variety of exploration and assessment guides are presented. A summary is included for users seeking overviews of specific topics.