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Gold/Mining/Energy : Rock Resources -- Ignore unavailable to you. Want to Upgrade?

To: Mike Gold who wrote (734)	1/29/1999 4:35:00 PM
From: the Chief	Read Replies (2) \| Respond to of 1996

Supergene enrichment and porphyry-type deposits. Mike here is the response from one of Rock Resources Geological specialists. Sorry I took so long. the Chief Enrichment zones are commonly associated with porphyry and other types of deposits in Chile. In the northern porphyry belt (ie. Collahuasi, Chuquicamata El Abra, El Salavador, Escondido...) the supergene chalcocite blankets and overlying copper oxide zones are high grade, >1%Cu and generally thick, >50m. In addition, many of these deposits have associated copper oxide zones located peripheral to the porphyry deposit. In the southern Chilean porphyry belt, (El Teniente, Disputada, Andina, Los Pelambres (ElPachon)... ROCK'S Tacho will be the next) enrichment zones do occur but to a limited extent. The enrichment zones here are generally thinner and less continuous. The reason for this is the climatic history. The southern area, those deposits in the Santiago region, had favorable conditions for the formation of mature supergene profiles, including chalcocite blankets and copper oxide bodies. However, this region subsequently experienced periods of glaciation, which removed enriched material. The upside here is that on average the porphyries of the south have higher primary ore grades and therefore do not have to rely on enrichment blankets to become economically feasible. The Coiron Property has several targets on them including the (i)Mount Tacho target and the (ii)Cerro Carmen-Cerro Macote Target. Mount Tacho and its related vein systems show evidence of supergene alteration and mineralization. This includes the surface exposures of leached rusty rock, the presence of copper oxides in and on fracture planes and the occurrence of chalococite in core samples. At present, our focus is proving up the presence of the porphyry system before looking for any high grade copper oxide deposits that may have formed in response to lateral migration of supergene fluids. Carmen-Macote occur as low hills in a valley at a much different elevation then Tacho and geologically show a different level of exposure. Here samples show both copper oxide minerals and copper-bearing sulfides suggesting glacial activity has removed any enriched zones from this area. But has provided surface exposure of the mineralized hydrothermal system. Sillitoe's knowledge on supergene enrichment zones and their parent porphyry systems is in large part, I would say (>)>80%, based on his observations of existing Chilean porphyry deposits. If one summarized in a table, as ROCK has (handed out at the Cambridge House Investment Conference this past week), the most important characteristics associated with porphyry Cu-Au deposits (derived from R.Sillitoe's, J. Hunt's, L. Gustafson's, etc... published observations) one would see that the targets on the Coiron Property match-up incredibly well. --------------------------------------------- Darryl D. Lindsay, Ph.D. Structural and Mineral Deposit Geologist