The four copper-gold porphyry targets currently known within the El Cobre Project -- Encinal, El Porvenir, Norte and Villa Rica -- occur over a strike length of about 4 kilometers and are defined by distinct Cu-Au soil anomalies, discrete, positive magnetic features and an extensive shallow IP chargeability anomaly. This shallow IP anomaly coalesces into a deep IP chargeability feature.
The largest surface target area is the Villa Rica zone, a roughly 2.5 kilometre by 1 kilometre area defined by a strong north-northwest trending magnetic-chargeability high and associated copper-gold soil geochemical anomaly. Recently (see Almadex news releases of March 19th, 2017 and April 10th, 2017) significant new gold porphyry mineralisation was identified in outcrop at the Raya Tembrillo target within the Villa Rica zone. First pass drilling at the Villa Rica commenced September 2017.
Between 1998-2013, limited RC and diamond drill testing at Encinal, El Porvenir, and Norte returned wide intercepts of porphyry copper-gold and narrow zones of intermediate sulphidation epithermal gold-silver mineralization.
Almadex's recent drilling programs, which commenced in 2016, have been successful in defining long intersections of good grade material, particularly in the Norte Zone.
Norte Zone: All five holes drilled in the Norte Zone prior to 2016 intersected porphyry-style mineralization. Hole 08-CBCN-022, one of the deepest holes drilled at Norte in 2008, returned values of 0.14% Cu with 0.19 g/t Au over 259 m and 08-CBCN-19 intersected 41.15 meters averaging 0.42 g/t gold and 0.27% copper to the end of the hole at 187.45 meters.
Drilling at the Norte Zone in 2016 and 2017 has resulted in the highest grade intersections to date at the El Cobre project, including 114.6 meters grading 1.33 g/t Au and 0.48% Cu (Hole EC-17-018, see press release of April 5, 2017), 80.5 meters grading 1.34 g/t Au and 0.46% Cu (Hole EC-16-012, see press release of October 24, 2016), and 70.45 meters grading 2.32 g/t Au and 0.59% Cu (Hole EC-17-026, see press release of July 25, 2017). Since the Norte Zone discovery, Almadex has been carrying out a systematic drill campaign to define this target. Future Norte drilling will focus on defining the high grade zone now emerging from the Norte drill program.
Encinal Zone: Hole CB5 (1998) intersected a highly altered breccia pipe containing fragments of stockwork veining and porphyry mineralisation across which 18.28 meters returned 1.42 g/t Au and 0.10% Cu. The breccia pipe occurs in a large alteration zone, IP chargeability high and magnetics low which has not been tested to depth.
On June 19, 2017 Almadex announced that a new area of exposed stockwork quartz veining and gold mineralisation had been identified in the Encinal Zone. On June 29, 2017 Almadex announced the results of initial drilling on this exposed stockwork (Hole EC-17-025) which returned results including 34.47 meters grading 0.73 g/t Au and 0.20% Cu. Almadex is currently following up these results with some additional drilling at Encinal.
El Porvenir Zone: Drilling has demonstrated that the system persists at least to 400 m depth. Significant copper and gold grades were intersected such as 0.16% Cu and 0.39 g/t Au over 290 m in hole DDH04CB1 in 2004. In addition, Hole EC-13-004 (2013) intersected 0.23% Cu and 0.36 g/t Au over 106 m, to a depth of 504 m, again indicating potentially significant mineralization at depth. No drilling has been conducted at El Porvenir since 2013.
All of the above zones remain open along strike and at depth, with numerous drill holes terminating in mineralization. In addition to the above, several anomalous areas remain untested by drilling.
Drilling at Norte re-commenced in June 2016, and was initially targeted to follow up interesting drill intersections generated by a former joint venture partner in 2008. Individual press releases since then can be accessed at the Updates and News section. A brief overview is also provided below along with a comparison to other gold/copper porphyry projects.
Since the Norte Zone discovery in August 2016 Almadex has been carrying out a systematic drill campaign to define this target. This drilling was initially based on large step-outs which have yet to define the limits of mineralisation. Current drilling is also focused on defining the high grade zone that is emerging from the drilling results. Continuous mineralization in hole 29 starting close to surface and continuing for over half a kilometer (534.9m of 0.90g/t Au and 0.30% Cu) shows the Norte Zone is developing significant tonnage as well as good grades. (See press release dated August 15, 2017)
The maps below show the plan view of recent drilling at Norte, along with a section view of some of the holes into the target.
The chart below compares the grade of some of the recent Norte drill intersections with the grades of some operating and development-stage gold-copper porhyry projects.
Finally, the plan map below shows the northing of the Norte drilling to date, and the targets which lie south of this drilling based on coincident IP chargeability, mag, and Cu and Au in soils.
On June 19, 2017 Almadex announced that a new area of exposed stockwork quartz veining and gold mineralisation had been identified in the Encinal Zone. On June 29th, 2017. Almadex announced the results of initial drilling on this exposed stockwork (Hole EC-17-025) which returned results including 34.47 meters grading 0.73 g/t Au and 0.20% Cu. Almadex is currently following up these results with some additional drilling at Encinal. A plan view of this target and cross section of hole EC-17-025 is provided below. [figures “Encinal Zone” and Section N2172437]
Historic drilling at the El Cobre has returned significant copper and gold values. Many of the holes have been shallow and have ended in copper-gold mineralization. Mineralogic and fluid inclusion studies show conclusively that the gold and copper-gold porphyry-style mineralization at El Cobre is not deeply eroded and great potential exists at depth, beyond the previous shallow drilling.
More importantly, these studies indicate that the mineralization is genetically unique like that of some of the Maricunga district gold-copper porphyry systems in Chile including the following deposits: