Ann: Drill Program Update - Riqueza, page-124

There are a dozen views on how OD was formed and the jury is still out. Back arcs, subduction zones, craton margin compression, etc. While the top of the ore body is 300-400m below surface now, it is highly likely that it has been at surface on one or more occasions in the distant past (including probably as sea floor spreading zones), it's been around for 1.6 billion years. Hence, supergene.

The bottom line is it was heavily oxidised zones at OD that generated the chalcocite. The data I have seen still makes the point that even at OD chalcocite while certainly present, is in a considerably lesser quantity than chalcopyrite and bornite. OD made a noise about it as it was easy to process, high copper % and made the start-up phase economics great.

Now back to Inca, there has been zero report of chalcocite from memory, extremely large quantities of various sulphide minerals reported (hence the excitement, 300 odd metres of sulphide minerals) and little or no oxides. The oxides would usually be present to take the reaction products of chalcopyrite or bornite being converted to chalcocite. Seems the obsession with chalcocite is getting people to forget what is there. Arsenopyrite, sphalerite, chalcopyrite and bornite. I have personally seen chalcopyrite in the NDIBK04 core at multiple intervals and a number of those not logged in the initial inspections by GA and co. I think it better to focus on what is there, or minerals that there are pointers suggesting it might turn up (eg gold in very substantial arsenopyrite intervals) rather than minerals that have not been described and for which there are no pointers.