McEwen Copper: Los Azules Progress Report #4

2022-08-04 04:13:21

Long intercepts with good grades

222.0 m of 0.95% Cu including 44.0 m of 1.38% Cu (AZ22158)
238.0 m of 0.58% Cu including 10.0 m of 1.10% Cu (AZ22161)
194.0 m of 0.56% Cu including 8.0 m of 1.04% Cu (AZ22163)

TORONTO, Aug. 04, 2022 (GLOBE NEWSWIRE) — McEwen Copper Inc., a subsidiary of McEwen Mining Inc. (NYSE: MUX) (TSX: MUX), is pleased to report the latest assay results from its Los Azules project, which continues to deliver long intercepts of good grades.

The drill program underway has three important objectives:

  • Improve confidence in the resource by converting Inferred mineral resources to the Indicated category;
  • Accelerate project advancement with metallurgical, hydrological and geotechnical drilling and
  • Test the limits of the depth extension of the higher-grade mineralization.

Results from this drilling program will be used to update the 2017 Los Azules PEA (Preliminary Economic Assessment). The updated version will be released in Q1, 2023.

The 2017 PEA was calculated using prices of $3/lb copper, $1,300/oz gold and $17/oz silver price. It projected robust economics, driven by large operating margins, large annual production, a short payback period and long mine life (link to the report: /home/default.aspxfiles/technical_reports/los_azules/LosAzulesPEA_Rev0_20171016.pdf). Drilling has halted for the winter and will resume in October when spring arrives in Argentina.

Earlier this year, Mining Intelligence ranked Los Azules as one of the world’s top five largest undeveloped porphyry copper deposits that is not already owned by a major mining company.

The opportunity to expand the deposit at depth remains open for further testing. While the median depth of drill holes within the Los Azules resource database is 175 meters (m), it is not uncommon for porphyry copper mineralization to extend well beyond a kilometer or more of depth. Numerous drill holes have encountered strong copper grades below the 2017 PEA pit bottom. Only three holes have been drilled to a depth of a kilometer and all encountered mineralization.

The highest-grade mineral domains at Los Azules are clearly the hydrothermal and magmatic breccias and late-stage quartz veins which can extend kilometres to depth. There are numerous examples of such deposits in Argentina and Chile. The most recent is Filo Mining’s spectacular assay results of earlier this year. The Filo deposit is 300 kilometres north of Los Azules, also in the San Juan province, Argentina.

The deepest occurrence of a breccia at Los Azules is at a hole depth of some 810 m in drill hole AZ1299 and deepest occurrence of late-stage quartz veins is found at 990 m down the same hole.

A dedicated exploration program associated with higher grade domains at Los Azules has not yet been conducted. Most holes drilled to date are vertical and intersect the breccias at very low angles. Improving our understanding of the nature and distribution of the highest-grade mineral zones at Los Azules is a priority for the upcoming drilling seasons.

The most recent drill results are presented below in the cross-section Figures 1 to 4. These display the current inclined and historic vertical holes, with histograms of total copper content along their length, overlayed on a simplified interpretation of overburden, leached, enriched and primary mineral zones, and the 30-year pit shell (shown by green line), as defined by the 2017 PEA.

Section 30-30′, shown in Figure 1, includes hole AZ22158, with an attractive intercept of 222.0 m grading 0.95% Cu, and including an interval of 44.0 m grading 1.38% Cu. Partial results were reported in the Los Azules Progress Report #3 published on June 23, 2022. Hole AZ22166 was stopped at the arrival of winter and will be completed in spring.

Figure 1 – Cross-section 30-30’

Figure 1 – Cross-section 30-30’

Section 36-36’, shown in Figure 2, received eight new drill holes during the recent campaign. The final intercept reported was hole AZ22162, which targeted the gap between hole AZ22138 (522.1 m grading 0.42% Cu) and AZ22139.

Hole AZ22162 returned 348.0 m grading 0.28% Cu, while also ending in enriched mineralization. It appears to correlate well with historic hole AZ0838 (188.3 m grading 0.27% Cu).  

Figure 2 – Cross-section 36-36’

Figure 2 – Cross-section 36-36’

Cross Section 44-44′ shown in Figure 3 presents hole AZ22163 (194.0 m grading 0.56% Cu). AZ22163 includes 8.0 m of high-grade 1.04% Cu and supports 146.0 m of high-grade 1.10% Cu reported in historic hole AZ0620. Hole AZ22167 (80.4 m grading 0.21% Cu) results are as expected and similar to the historic hole LA0402.

Figure 3 – Cross-section 44-44’

Figure 3 - Cross-section 44-44’

Cross-section 48-48′ shown in Figure 4, profiles three new holes. Hole AZ22149 (296.4 m grading 0.55% Cu including 54 m of 1.38% Cu), drilled just west of the center of the section, was released in our June 23 exploration update. Hole AZ22161, drilled east of the center of the section, with 238.0 m grading 0.58% Cu and including 10 m of 1.10% Cu, supports historic intercepts in adjacent holes AZ1060A (221.0 m grading 0.53% Cu) and AZ18136 (194.0 m grading 0.43% Cu), all below the 30-year pit shell, indicating significant potential for mineralization at depth.

Holes AZ22147 and AZ22165 were drilled off the west and east flanks to delimit margins of the deposit and did not encounter significant mineralization.  

Figure 4 – Cross-section 48-48’

Figure 4 - Cross-section 48-48’

Figure 5 – Locations of the cross-sections on the plan of the deposit

Figure 5 - Locations of the cross-sections on the plan of the deposit

The Los Azules deposit is sequentially sub-divided into 50 m cross sections beginning at the southeast end of the deposit and progressing to the northwest. Section 36-36’ is approximately the mid-section of the deposit. As a matter of cross-referencing results presented in the Los Azules Progress Report #3 published on June 23, 2022, note that Section 36-36’ was previously identified as Section A-A’ and Section 48-48’ as Section C-C’. Section 40-40’ identifies with Section B-B’ and was not included in this release as no new results have been added there.

Drilling resumes in October, and the plan is to complete 45,500 m.

Link to Drilling Results and Hole Collar Locations and Lengths for January to May 2022 at Los Azules: https://www.mcewenmining.com/files/doc_news/archive/2022/202208_LosAzules/2022_08_Los_Azules_Update_4.xlsx (alternatively see Tables 1 and 2 at the end of this press release).
          

Technical Information  

The technical content of this news release has been reviewed and approved by Stephen McGibbon, P.Geo, SVP Exploration of McEwen Mining and a Qualified Person as defined by NI 43-101. 

All samples were collected in accordance with generally accepted industry standards. Drill core samples usually taken at 2 m intervals are split and submitted to Alex Stewart International laboratory in Mendoza, Argentina for the following assays: gold determination using fire assay fusion and an atomic absorption spectroscopy finish (Au4-30); a 39 multi-element suite using ICP-OES analysis (ICP-AR 39); copper content determination using a sequential copper analysis (Cu-Sequential). An additional 19-element analysis (ICP-ORE) was performed for samples with high sulfide content.

The Company carries out a Quality Assurance / Quality Control program consistent with NI 43-101 and industry best practices utilising a combination of standards and blanks approximately one in every 25 samples. Results are monitored as the final certificates are received and any re-assay requests are sent back immediately. Pulp and prep duplicate sample analyses are also taken as part of the QAQC process. Approximately 5% of sample pulps are sent to a secondary laboratory for check assays. In addition, the assay lab performs its own internal QAQC checks with results available in the certificates for review by the Company.

Table 1 – Drill Results January-May 2022 at Los Azules 

Hole-ID Section Predominant Mineral Zone From (m) To
(m)
Length (m) Cu
(%)
Au
(g/t)
Ag
(g/t)
Comment
AZ22137A 36 Total 133.0 557.3 424.3 0.47 0.027 0.008  
incl   Enriched 133.0 342.0 209.0 0.49 0.028 0.016  
and   Primary 342.0 557.3 215.3 0.44 0.026 0.001 incl. 8m of 1.00% Cu in Primary
AZ22138 36 Total 138.0 660.1 522.1 0.42 0.064 1.883  
incl   Enriched 138.0 348.0 210.0 0.60 0.064 2.180 incl. 28m of 0.87% Cu in Enriched
and   Primary 348.0 660.1 312.1 0.30 0.065 1.683  
AZ22139 36 Total 114.5 282.6 168.2 0.08 0.060 1.447  
incl   Enriched 206.5 282.6 76.1 0.12 0.032 1.164  
AZ22140 36 Total 117.4 342.8 225.4 0.16 0.030 1.117  
incl   Enriched 117.4 314.0 196.6 0.16 0.032 1.173  
and   Primary 314.0 342.8 28.8 0.16 0.019 0.732  
AZ22141 40 Total 183.1 551.0 367.9 0.50 0.069 1.535  
incl   Enriched 183.1 360.0 176.9 0.50 0.044 1.437  
and   Primary 360.0 551.0 191.0 0.50 0.092 1.625  
AZ22142 36 Total 92.0 511.1 419.1 0.79 0.152 3.508 incl 32m of 1.11% Cu &
incl   Enriched 92.0 278.0 186.0 0.93 0.095 3.544 104m of 1.00% Cu in Enriched
and   Primary 278.0 511.1 233.1 0.67 0.198 3.479 46m of 1.59% Cu in Primary
AZ22143 36 Total 92.5 403.0 310.5 0.20 0.015 0.880  
incl   Enriched 92.5 266.0 173.5 0.22 0.016 0.985  
and   Primary 266.0 403.0 137.0 0.18 0.014 0.747  
AZ22144 36 Total 58.0 506.6 448.6 0.30 0.02 0.84  
incl   Enriched 58.0 204.0 146.0 0.31 0.01 0.52  
and   Primary 204.0 506.6 302.6 0.29 0.02 1.00 incl 104.6m of 0.48% Cu
AZ22145 40 Total 76.0 257.0 181.0 0.18 0.02 1.90  
incl   Enriched 76.0 194.0 118.0 0.16 0.03 2.25  
and   Primary 194.0 257.0 63.0 0.21 0.01 1.26  
AZ22146 40 Total 91.0 421.5 330.5 0.83 0.11 2.30  
incl   Enriched 91.0 394.0 303.0 0.86 0.11 2.26 incl 103.4m of 1.31% Cu
and   Primary 394.0 421.5 27.5 0.50 0.10 2.76  
AZ22147 48 Total 60.0 240.8 180.8 0.03 0.02 0.50  
incl   Enriched 60.0 67.0 7.0 0.10 0.08 1.27  
AZ22148 40 Total 76.0 315.0 239.0 0.26 0.02 1.01  
incl   Enriched 76.0 212.0 136.0 0.33 0.02 0.85  
and   Primary 212.0 315.0 103.0 0.16 0.02 1.23  
AZ22149 48 Total 131.6 428.0 296.4 0.55 0.04 1.62  
incl   Enriched 131.6 278.0 146.4 0.34 0.02 0.32  
and   Primary 278.0 428.0 150.0 0.76 0.06 2.91 incl 54m of 1.38% Cu from 376m
AZ22150 44 Total 78.0 257.4 179.4 0.14 0.01 0.53  
incl   Enriched 78.0 126.0 48.0 0.04 0.01 0.25  
and   Primary 126.0 257.4 131.4 0.17 0.01 0.63  
AZ22158 30 Enriched 72.0 294.0 222.0 0.95 0.09 1.57 incl 44m of 1.38% Cu from 144m
and   Primary 294.0 300.0 6.0 0.34 0.05 0.43  
AZ22161 48 Enriched 116.0 354.0 238.0 0.58 0.07 1.19 incl 10m of 1.10% Cu from 156m
AZ22162 36 Enriched 102.0 450.0 348.0 0.28 0.40 1.13 incl 2m of 0.86% Cu from 232m
AZ22163 44 Enriched 92.0 286.0 194.0 0.56 0.04 0.68 incl 8m of 1.04% Cu from 98m
AZ22164 38 Leached 18.0 242.0 224.0 0.04 0.02 1.32  
AZ22165 48 Leached 24.5 200.0 175.5 0.04 0.04 1.27  
AZ22166 30 Enriched 82.7 199.6 116.9 0.13 0.02 0.81 incl 53.6m of 0.25% Cu from 146m
AZ22167 44 Enriched 72 152.4 80.4 0.21 0.02 0.78 incl 54.4m of 0.25% Cu from 98m

Table 2 – Hole Collar Locations and Lengths for January-May 2022 Drill Results at Los Azules  

HOLE-ID Azimuth Dip Length Loc X Loc Y Loc Z
AZ22137A 250 -70 557.3 2383289 6559336 3667
AZ22138 250 -78 660.1 2383569 6559450 3676
AZ22139 70 -79 282.6 2383725 6559494 3719
AZ22140 160 -76 342.8 2383687 6559463 3701
AZ22141 250 -78 551.0 2383530 6559636 3669
AZ22142 70 -65 511.1 2383286 6559334 3667
AZ22143 250 -70 403.0 2382768 6559131 3723
AZ22144 250 -70 506.6 2382889 6559204 3688
AZ22145 250 -73 257.0 2382912 6559411 3628
AZ22146 250 -75 422.0 2383406 6559591 3644
AZ22147 250 -68 241.0 2382558 6559708 3642
AZ22148 250 -75 315.0 2383106 6559482 3647
AZ22149 70 -77 428.0 2382879 6559875 3618
AZ22150 70 -82 257.4 2382670 6559536 3661
AZ22158 250 -65 300.0 2383561 6559115 3627
AZ22161 250 -81 354.0 2383575 6559120 3658
AZ22162 250 -70 450.0 2383442 6560030 3641
AZ22163 73 -70 286.0 2383725 6559494 3719
AZ22164 70 -68 242.0 2383429 6559812 3648
AZ22165 70 -71 200.0 2383733 6559603 3726
AZ22166 250 -70 199.6 2383652 6560106 3672
AZ22167 70 -80 152.4 2383727 6559175 3675
Coordinates listed in Table 2 based on Gauss Kruger – Campo Inchauspe Zone 2  

  


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