Given the multitude of veins identified at surface and the three manto sequance that has been reported, I was expecting to see more mantos intercepted by early stage drilling. In a perfect theoretical world, increasing depth should result in more numerous and thicker veins and mantos closer to the fluid/heat source. Ideally, at a certain depth within the limestone host rocks, the Humaspunco veins, mantos, and breccia pipes should coalase from individual, discrete, high grade structures into a larger, more homogenously low-medium grade mineralised skarn (i.e. potentially Pb, Zn, Cu, Ag, Au enriched), that would represent a large volume of mineralised rock that is (again ideally), economical to extract. Skarn occurs when limestone is metamorphosed by contact with a hot magma body and its associated, metal-enriched hyrdothermal fluids. Below the skarn, the system would transition into a mineralised porphyry body with disseminated Cu and or Au within the granitic style rocks derived from the cooling magma. That would be a simplified cross section in an ideal senario and were drilling to delineate such a system the SP would move up*.
So far we have not had any mantos reported in the subsurface and that really surprises me. There is obviously a very large amount of fluid that has pulsated through Humaspunco in a series of generations (noted in yesterday’s announcement with cross-cutting sulfide veinlets). Given this large volume of fluids and the stratified nature of Humaspunco Hill, it seems odd that a series of subhorizontal mantos have formed near the present day surface but not below. Additionally, numerous veins are now known to extend to depth while increasing in size and intensity suggesting the system is not simply constrained to the upper few hundred meters of the hill. If the fluid pressure during mineralisation was higher at depth, and a large amount of fluid was in existance, it would seem logical this pressure would have penetrated further into the host rock and do so preferencially along more porous/permeable layers of limestone and thus form additional mantos at depth. So far none have been reported.
Possibly, an argument could be made that if fluid pressure was very high and an pre-exisiting set of fractures/faults/planes of weaknesses occurred at Humaspunco then the mineralising fluids might simply have pushed upwards very, very quickly to form the veins, with mantos forming near the present day surface where pressure was lower and the fluid could moved both vertically and laterally. The pre-exisiting structures were likely there given that Humaspunco occurs very close to the apex of a massive regional fold; the entire hill appears riddled with accommodating structures so the ground preparation is – the favourite word for Riqueza – textbook. I’m not too sure the theory above but if it was somewhat true then I would also suggest that a) in the high pressure area of the system close to the fluid source the host rock should be fluid saturated which could assist formation of disseminated sulfides (note that for sulfides to form the fluid not only has to be enriched, but there also needs to be a reason for the metals to precipitate such as a drop in pressure, temperature, change in fluid chemistrycaused by additional younger fluids, interaction with the calcareous host rocks, etc), and b) that the absence of reported mantos in the drilling to date might suggest that depth to the heat source at Humaspunco is not too much deeper. Both a and b would tend towards positives for Riqueza exploration.
However, for me, the lack of reported mantos in the drilling is a flag that should be commented on and I do so to ensure I give a balanced view to those reading the thread. If the mantos are not there then that is a negative for economics for Humaspunco, but I don’t necessarily see it as a simple night and day situation or as a show-stopper for the project. As mentioned before, the ultimate answer will not be comments from the company but solely assay results. I hope and expect to see wider zones of low-medium grade material occuring at depth interspersed with discrete, high grade zones. Writing ASX announcements is a pretty tricky thing to do balancing enthusisam and optimism with truthful observations and rational discussion while also satisfying investors and reporting regualtions. I wouldn’t be surprised if the company is somewhat conservative in the early reporting while assays are awaited. They have plenty of funds so no need to spike the price for a CR so in the medium term goal should be to complete a good drill program and see the SP slowly appreciate. It is the assays results that will help this.
Hope this helps. Sorry it’s long-winded!
Cheers,
Bornite
*Alpaca Army members can insert their preferred SP action here possibly with a few additional adjectives as well ; )
ICG Price at posting:
1.5¢ Sentiment: Buy Disclosure: Held
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