Green rocks are a common alteration feature of porphyry deposits,  but it can be hard to decipher meaningful information from them for exploration. This week we dive into the results of years of multi-organization research and studies to see what has been learned, review a case study at Oyu Tolgoi, Mongolia and get a 'reality check' with from an industry perspective. First off David Cooke of the CODES program at the University of Tasmania, Hobart provides the framework for how these zones of alteration form and what minerals and techniques can be used to help decipher patterns within them. The detailed understanding of variations in mineral chemistry are based on years of research and the input of several institutions and many researchers. Next we talk with Lisa Hart-Madigan who recently completed a PhD at Imperial College, London, UK. She provides a deep dive into her work there to characterize the propylitic alteration. In the last segment, Tim Ireland, FQM, provides some real world experience in exploration globally and suggests where these techniques might actually be helpful in guiding programs. Theme music is Confluence by Eastwinds eastwindsmusic.com