ALTERATION and ZONATION
Hydrothermal Alteration shows as a distinct reddish and multicolored coloration to soil and outcrop. Between the breccia pipes and extending to untested ground there is a distinct “bluish” patch of material visible from satellite imagery. The rock and soil material near the patches have been sampled and the results show very high mineralization where there is a set of three magnetic highs (see fig. 4 near the chalcanthite outcrops).
There is a strong epidote halo around clasts and veins. PIMA work shows most core hosts clay-chlorite-sericite alteration accompanied by moderate to strong quartz-limonite stockwork. Hydrothermal sericite at the system has been radiometrically Ar-Ar dated as 14.3 Ma, confirming a very favorable Miocene age consistent with post-infirnillo age intrusive activity. PIMA results show alteration reached sericitic stage.
Preliminary copper mineral zonation based on MIL-002 core review by Milena Resources LLC suggests
1) surficial chalcanthite and covellite/enargite…(As in geochem)
2) shallow covellite-cpy-chalcocite (sectile sooty black specks) to 100+ meters,
3) indistinct blue-gray coppers appear in addition to covellite/chalcopyrite…(enargite/digenite possible) below 100m
4) chalcopyrite-A-vein pyrite. Drilling, at least for MIL-002 has penetrated the Calcite-Anhydrite-Enargite fields and the magnetite field but seems above the “bornite line” (fig 17) (red colored sulfides indicating peacock bornite was not found despite careful search at 20-30x but there are many small indistinct bluish crystals at depth in MIL-002 that could be bornite or digenite, some of which shows up on surface sampling by Teck. (fig. 16).
Core examination reveals clast-filled veins showing cemented, quartz-rimmed, fine-grained pyritic clasts from deep parts of the system (see Figures 9-11).
The cores are dominated by sericite-chlorite-quartz alteration with pyrite, chalcopyrite, probably leached out gypsum and residual quartz. Core and core photos can be made available and includes 2,087 meters of core drilled.
Copper-bearing mineralization, blueish covellite/enargite mineralization, chalcocite disseminations and pyrite/chalcopyrite appears hosted within breccia fragments, in veinlets and in matrix between fragments. The presence of anomalous As in geochemical analysis suggests that some of the indistinct gray mineralization is enargite or other sulfosalts. Open space quartz filling is difficult to recognize but present (see Fig 4 above inset, core at 88m).
Relatively fresh greenish propylitic rock is usually at found deeper than 50-100 meters. At depth, usually below 75 meters there are multiple meter intersections of non-greenish quartz rich granodiorite/tonalite thought to be dikes intruding the breccia from the likely porphyry intrusive at depth.
The “steamed” part of the porphyry system outcrops with clays and siliceous zones. There is pyrite rubble open space filling in core at 88m in DDH MIL-002. The steamed cap has not been mapped but there are suggestions it extends to about 75 meters. High sulfidic covellite-chalcocite mineralization with traces of chalcopyrite grades into copper minerals that are digenite-like, (blue-gray sulfide bearing disseminations) and pyrite/chalcopyrite in simple non-druzy “A-type” vein-like assemblages with little or no vein quartz spread out over hundreds of meters.
PIMA work on core indicates widespread propylitic and argillic alteration and irregular sericitic alteration. Large parts of the Project área, including the target, are concealed by red soil and moraine deposits.