Meridian Mining Plc press release
Meridian Defines Initial Exploration Target of 3.2 - 7.3 mt @ 3.0 - 3.2 g/t AuEq at Santa Helena
TSX - Toronto Stock Exchange · Gold · Copper · Silver · Zinc · Lead · Manganese · Iron · Tin · United Kingdom
Exploration Target is contained within only 1.4km of the ~3km prospective trend
LONDON, UK / ACCESSWIRE / December 5, 2023 / Accesswire / Meridian Mining UK S (TSX:MNO)(OTCQX:MRRDF)(Frankfurt:2MM)(Tradegate:2MM) ("Meridian" or the "Company")is pleased to report that it has assessed the geological potential of the Santa Helena mine area ("Santa Helena") based on new and historical data, generating an initial Exploration Target with a tonnage range of 3.2 -7.2 Mtgrading between3.0 - 3.2g/t AuEq*, which gives a potential high-grade metal inventory range of between 306,000 to 763,000AuEq ounces, located within 10km of the proposed Cabaçal mill site1.
The Company is also reporting further strong intercepts at Santa Helena including CD-359: 36.6m @ 1.3g/t AuEqfrom 13.0m; and CD-378: 5.9m @ 5.5g/t AuEqfrom 38.3m. These follow early positive results2from the Company's verification and extensional drilling program, and now highlight an expansion of Santa Helena's mineralization across strike, and at depths suitable to open pit development potential. Further drill results remain pending.
Highlights Reported Today
Meridian reports Exploration Target for Santa Helena mine area of 3.2 - 7.2 Mt @ 3.0 - 3.2g/t AuEq; Exploration Target's contained metal is between 306,000 to 763,000 AuEq ounces; Mineralization grades 1.0 - 1.1g/t Au, 0.7 - 0.8 % Cu, 20.0 - 26.3 g/t Ag and 2.8 - 3.0 % Zn; Exploration target restricted to 1.4km of the ~3km prospective trend;
Santa Helena's drilling expands and confirms shallow VMS Au, Cu, Ag and Zn mineralization; CD-359: 36.6m @ 1.3g/t AuEq(0.6g/t Au, 0.4% Cu, 8.4g/t Ag & 0.8% Zn) from 13.0m;
Including:
9.4m @ 1.9g/t AuEq(1.3g/t Au, 0.6% Cu, 15.1g/t Ag & 0.5% Zn) from 13.0m; CD-378: 5.9m @ 5.5g/t AuEq(1.9g/t Au, 1.3% Cu, 33.5g/t Ag & 5.6% Zn) from 38.3m; and
Expansion of drilling into Santa Helena's prospective ~2km eastern extension is planned for 2024.
*_The potential quantity and grade of an Exploration Target is conceptual in nature. There has been insufficient exploration to define a mineral resource, and it is uncertain if further exploration will result in the target being delineated as a mineral resource. The metal equivalence formula is based on the historical Santa Helena resource report_3_, calculated as AuEq based on gold being the dominant metal of the Cabaçal VMS camp, as the expectation is that Santa Helena's mineralization will be evaluated for processing through a centralized facility at the Cabaçal mill with the addition of a zinc circuit. True width is considered to be 80 to 90% of intersection width._
Mr. Gilbert Clark, CEO, comments: "Today Meridian continues to confirm the tremendous value upside opportunity that the Cabaçal belt presents. Santa Helena's high-grade Exploration Target of 306,000 to 763,000 ounces of gold equivalent, within a small tonnage and high-grade ranges, presents a very exciting upside opportunity for both the Cabaçal belt and for Meridian's shareholders."
"Looking to the medium term growth plans, utilizing a robust Exploration Target and continuing strong drill results, we will evaluate Santa Helena's potential for contributing additional high-grade mineralization to Cabaçal's future. Being within ten km of the advanced Cabaçal Mine project, if ongoing work at Santa Helena proves successful, future economic studies will not need to carry the capital expenditure of building a stand-alone mill. After a great year of advancement of the Cabaçal belt in 2023, including the submission of the Cabaçal mine's Preliminary Licence Application, we look forward to the further strong progress in 2024."
Santa Helena Initial Exploration Target
The Santa Helena mine area provides for the continuation of Meridian's low-risk investment model of targeting prospects with a high degree of potential and untested upside. A robust geological and mineralization model has been achieved by incorporating the results from historical drill campaigns, geology, and mining records, with Merdian's recent results from diamond drilling, trenching, mapping and geophysical surveys. This, with the removal of the limited mined areas, was then used as the basis for the reasonable ranges of tonnes and contained metals defined within the Exploration Target.
The VMS mineralization has been modelled and the plan view ("Figure 1") shows a strong correlation to the historical geological maps and reports. The long sections indicate that the mineralization again strongly follows the known geology of a continuous mineralized trend ("Figure 2").
Figure 1: Upper Range Santa Helena Upper Range Exploration target footprint in relation to the historical resource outline.
The Santa Helena database consists of data generated from multiple campaigns of surface and underground drilling and sampling, summarized as follows:
| Campaign | Code | Number | Meterage | Average Depth (m) | | Historical DDH (BP Minerals) | JUCHD | 80 | 8,301.42 | 103.77 | | Meridian DDH | CD | 14 | 731.1 | 52.22 | | Historical DDH (Prometálica) | FS | 35 | 1,170.81 | 33.45 | | PM | 39 | 2,487.98 | 63.79 | | | Historical Channels/Trenches (BPM/RTZ) | C2C_TR | 14 | 707.66 | 50.55 | | Grand Total | 182 | 13,398.97 | 73.62 | | | | | | | | | Campaign | Code | Number | Meterage | Average Length (m) | | Grade Control (Prometálica) | FP | 249 | 793.61 | 3.19 | | CAN / M | 90 | 129.4 | 1.44 | | | Grand Total | 339 | 923.01 | 2.72 | |
Table 1: Summary of Santa Helena Exploration Target database.
Surface drilling and locally trenching to the east was historically conducted on nominally 50 x 25 m spaced sections along a strike length of ~ 1,350m, with a cross-strike footprint of ~130 -220m, with some outlying holes. Spacing was not always regular, and a combination of vertical and inclined holes were drilled. Sectional azimuth varied from 10 to 35 degrees across the deposit. Meridian has since concluded 1,258m of drilling including 6 twin holes and 18 resource delineation holes within and outside the historical resource envelope. The model utilizes 14 of Meridian's holes (731.1 m of drilling) for which results were available.
Figure 2: Top: long section looking north of Lower Range Exploration Target (after depletion), Bottom long section looking north of Upper Range Exploration Target (after depletion).
Geological modelling was completed generating a mineralization wireframe at a 0.3g/t AuEq cut-off grade, consistent with the resource cut-off grade of the Cabaçal deposit. Modelling of key lithologies included bounding post-mineralization gabbro sills which are present in the footwall and hangingwall of the deposit. A block model constrained by the interpreted mineralized bodies was constructed with the parent cell size of 10 mE x 10 mN x 5 mRL. Drillhole sample intervals have been composited to 1 m length and were used to interpolate all main modelled grades (Zn, Pb, Cu, Au, Ag) into the block model using inverse distance2and ordinary kriging (OK) interpolation techniques. Block grades were validated both visually and statistically and all modelling was completed using Leapfrog software.
To estimate the grades inside of the 0.3g/t AuEq cut-off grade wireframe, 1,644 samples of Au, 1,715 of Cu, 1,606 of Ag, 1,745 of Zn and 1,714 of Pb were used. For the lower limit of the exploration target, the unsampled drilling intervals were replaced by zero grade. Meridian's drilling indicates that like at the Cabaçal mine, areas of mineralization were left unsampled due to a particular commodity or development focus. For the upper limit, the unsampled intervals were omitted and the wireframe projected along a trend considered reasonable based on geometry and geological logging.
The search radius used was 70m x 70m x 10m for the major, semi-major and minor axes respectively, the same used to classify inferred resources in the Cabaçal deposit, with restrictions of a minimum of 2 and a maximum of 10 samples. For the interpolation of the grades, dynamic anisotropy was used with the geometry of a synclinal fold plunging up-plunge towards the east-south-east.
To evaluate the reconciliation of the Exploration Target with historical mining production of the vendors, Prometálica, the block model was resized to 4 mE x 4 mN x 2 mRL to better adhere to the geometry of the mining void. The difference in the estimated tonnage was -0.6%, and for the grades the variation was, +9.3% for Au, +4.5% for Cu, -2.9% for Ag, and -5.7% for Zn ("Table 2"). Lead production was not reported and is currently not contributing to the metal equivalence formula. Production is based on the historical digital archives of the Run-of-Mine monthly records of the Prometálica geology department, from October 2006 to August 2008. These Run-of-Mine production figures closely align with the modelled estimate, providing confidence in the Exploration Target's potential. The estimated range in tonnage and grade for the Exploration Target after mining depletion are 3.2 -7.2 Mt @ 3.0 - 3.2 g/t AuEq / 2.0 - 2.2% CuEq (1.0 - 1.1 g/t Au, 0.7 - 0.8% Cu, 20.0 - 26.3 g/t Ag & 2.8 - 3.0 % Zn; "Table 3"; "Table 4"). Metal equivalence is based on the historical SRK resource report, with metal prices applied from the Meridian's Cabaçal PEA dated March 6, 2023 (AuEq = (Au(g/t) 65%Recovery) + (1.492Cu% 89%Recovery) + (0.474Zn% 89%Recovery)) + (0.008Ag(g/t) 61%Recovery)). Recovery formulas will be updated with future testwork programs.
| Reconciliation | | | | | | | Item | Mass (t) | Zn_pct | Cu_pct | Au ppm | Ag ppm | | Historical Prometálica Production Report | 439,813 | 6.65 | 1.62 | 1.77 | 43.02 | | Meridian Estimation - Void Model | 437,290 | 6.27 | 1.69 | 1.94 | 41.79 | | Difference | -0.6% | -5.7% | 4.5% | 9.3% | -2.9% |
Table 2: Comparison of the model with Run of Mine production records of Santa Helena.
| Exploration Target | | | | | | | | | | | | Item | Mt | Au | Ag | Cu | Zn | Pb | AuEq | AuEq | CuEq | CuEq | | (g/t) | (g/t) | (pct) | (pct) | (pct) | (g/t) | (koz) | (pct) | (Mlbs) | | | | Pre-Mining - Upper Range Exploration Target | 7.8 | 1.2 | 27.2 | 0.8 | 3.2 | 0.7 | 3.4 | 854 | 2.3 | 393 | | Pre-Mining - Lower Range Exploration Target | 3.6 | 1.1 | 22.7 | 0.9 | 3.3 | 0.6 | 3.4 | 397 | 2.3 | 183 | | Mining Depletion | 0.4 | 1.8 | 43.0 | 1.6 | 6.7 | 1.0* | 6.4 | 91 | 4.3 | 42 | | Upper Range Exploration Target
(after depletion) | 7.3 | 1.1 | 26.3 | 0.8 | 3.0 | 0.7 | 3.2 | 763 | 2.2 | 351 | | Lower Range Exploration Target
(after depletion) | 3.2 | 1.0 | 20.0 | 0.7 | 2.8 | 0 .6 | 3.0 | 306 | 2.0 | 141 |
Table 3: Exploration Target for the Santa Helena Deposit, with recovery-factored gold equivalent and copper equivalent content. Individual metal grades are pre-recovery.
_* Lead production was not officially reported, but figures indicated based on metallurgical feed reports aligning well with modeled calculation. Lead does not contribute to the metal equivalence formula._
| Item | Mt | Au | Au_rec | Ag | Ag_rec | Cu | Cu_rec | Zn | Zn_rec | | (koz) | (koz) | (koz ) | (koz ) | (Mlbs) | (Mlbs) | (Mlbs) | (Mlbs) | | | | Pre-Mining - Upper Range Exploration Target | 7.8 | 291 | 189 | 6793 | 4144 | 143 | 127 | 544 | 484 | | Pre-Mining - Lower Range Exploration Target | 3.6 | 123 | 80 | 2666 | 1626 | 69 | 61 | 264 | 235 | | Mining Depletion | 0.4 | 25 | 16 | 608 | 371 | 16 | 14 | 64 | 57 | | Upper Range Exploration Target after depletion | 7.3 | 266 | 173 | 6185 | 3773 | 127 | 113 | 480 | 427 | | Lower Range Exploration Target after depletion | 3.2 | 98 | 64 | 2058 | 1255 | 53 | 47 | 200 | 178 |
Table 4: Exploration Target metal contents, before and after metallurgical recovery factoring.
An average bulk density values of 2.94 - 2.97 t/m3 was derived for the deposit, based on interpolation of 267 density readings on drill core. Values were derived by immersion techniques in Meridian and historical campaigns of drilling.
The estimated potential quantity of tonnes and grades are conceptual in nature as there has been insufficient data and evaluation to support estimation of a Mineral Resource. Tonnages and grades are expressed as ranges that are considered appropriate for the Exploration Target. There is no certainty that further exploration, verification drilling, or twinned drilling will result in the estimation of a Mineral Resource. The Exploration Target is not to be considered in any way to represent a Mineral Resource or Ore Reserve.
Steps being taken to update the Exploration Target to a resource include:
Independent QP review - field checks completed by H&SC associate, Marcello Batelochi. Full review of database to be conducted after receipt of additional assay results; Update of surface relief topographic model for open pit development assessment - completed with high-precision Lidar survey flown by Brazilian Contractor, Embratop; Resampling checks on available historical drill core - completed; Maximizing collar surveys of all historical holes that can be located at surface (over 50% confirmed); Assess spatial shift between modern surfaces and historical theodolite-based surfaces (Current reconciliation of coordinates based on drill holes, mine entrance and ventilation shaft indicate a shift of x-3.3m, y-3.6m, z+12.9m between mine database records and SIRGAS200 grid; Resampling umpire checks on available historical pulps - in progress; Compilation of historical records - completed for assays and geological coding; compilation of recovery data and geotechnical data in progress; Addition of more density data into the database - proceeding in parallel with Meridian drilling; Completion of 50 x 50m infill check and extensional cross-strike drilling, with 25 x 25m infill test area - objectives of current program and continuing into 2024 campaign; Final spatial review of collar and void underground data integrity; Review metallurgical recovery assumptions with new testwork program, including the assessment of potential for Pb concentrate with precious metal credits, and assessment of oxide - transition zone recoveries which affect ~20% of the exploration target: scheduled for 2024; and Checks of historical records of plant throughput and tailings grade to compare against the geology department run-of-mine production records - ongoing.
Scope remains to test further potential for extension to the mineralized system, along the geophysical anomalies projecting along strike from Santa Helena.
Opportunities to recover a lead concentrate will be assessed as part of the future metallurgical test programs. The historical processing facility did also not include a gravity circuit. Gravity recoverable gold is anticipated at least in the oxide zone, with past surface geochemical surveys identifying a surface gold in soil anomaly at Santa Helena by pan concentrate methods.
Santa Helena Historical Resource Estimate
SRK was previously commissioned by the Cabaçal Vendors to undertake a resource study on the Monte Cristo (Santa Helena) Zn Deposit in 2007 ("Table 5"). This estimate was last updated in a report dated 30 May 2007. The estimation procedure used three iterations of the inverse distance squared method on composited drillhole data with progressively longer search ranges. A Zn Equivalent % calculation was applied for reporting the estimates (ZnEq % = Zn% + (2.14 Cu%) + (0.39 Au ppm)+ (0.007* Ag_ppm); Metallurgical Recovery = 89% Zn, 89% Cu, 65% Au, 61% Ag; Au price USD 570 / oz; Ag price USD 11 / oz, Cu price USD 3.36/ lb; Zn price = 1.57 / lb). A qualified person has not done sufficient work to classify the historical estimate as current mineral resources or mineral reserves; and the issuer is not treating the historical estimate as current mineral resources or mineral reserves. The 2007 historical resource does not account for final depletion.
Table 5: Historical Santa Helena 2007 Resource Estimate.
The historical resource had a number of limitations reducing its tonnage compared to the current Exploration Target range:
The historical resource was quoted at a 3% Zinc Equivalent cut-off grade, reducing the amount of lower grade mineralization at reasonable grades that could alternatively be considered for open-pit development; The historical resource estimate did not incorporate data from mineralization intersected in BP trenching and drilling programs at the eastern end of the deposit; Checks against original BP maps and reports retrieved from historical archives, coupled with field checks, indicated than a number of holes were wrongly placed in the database; and New drilling indicates a greater cross-strike footprint of mineralization than originally modelled.
Santa Helena Drill Program
Santa Helena is a Cu-Au-Ag & Zn VMS deposit located ~9km to the southeast of the Cabaçal Mine in Mato Grosso Brazil. It has over 10,000m of historical drilling and is one of a series of exploration targets along the 11km Cabaçal Mine Corridor. The Company commenced initial drilling in August 2023 as part of a verification program, to validate the historical data in line with NI43-101 requirements, and to initiate scout drilling for potential extensions defined by geophysics. The Company's compilation of historical drill data indicated that many past holes were not completely sampled, that reconciliation of surveyed drilled positions and mine workings suggested that the high-grade massive sulphide mineralization was only partially mined. and that extensions of near-surface mineralization to the south and to the east were also not integrated into the historical resource calculations4. The Company has concluded that this historical resource area is considered open.
Figure 3: Santa Helena drill results, with 2.0km eastern exploration extension, and newly emerging target area remaining open to the southeast.
The Company has completed twenty-four holes to date. Initial results from holes drilled along the main trend for resource verification were very positive, confirming high-grade massive to semi massive near-surface mineralization5. Further drilling across strike into a geochemical anomaly located south of the historical resource also confirmed strong mineralization, locally increasing the cross-strike footprint of mineralization by up to 300%6. These results have included:
CD-311: 19.1m @ 1.9g/t AuEqfrom 8.0m; including 4.9m @ 6.8g/t AuEqfrom 22.2m; CD-321: 23.1m @ 1.5 g/t AuEqfrom 6.1m, including 3.6m @ 4.9 g/t AuEqfrom 10.0m; CD-325: 14.9m @ 4.6 g/t AuEqfrom 26.3m; CD-329: 6.8m @ 7.4g/t AuEqfrom 38.7m; CD-332: 5.8m @ 6.8g/t AuEqfrom 32.2m; CD-335: 7.2m @ 6.0g/t AuEqfrom 35.5m; CD-336: 30.7m @ 1.1g/t AuEqfrom 6.0m, including: 5.7m @ 2.2g/t AuEq; and CD-351: 11.7m @ 2.0g/t AuEqfrom 27.0m, including 5.4m @ 2.8g/t AuEqfrom 27.0m.
The latest results ("Table 6"; "Figure 3") have been returned from a range of positions throughout the deposit.
Additional drilling across strike from the historical resource has returned further shallow mineralization with a wide zone intersected in CD-359, located 55m along strike from CD-336. Further drilling is in progress to extend this position eastwards along strike.
CD-359: 36.6m @ 1.3g/t AuEq(0.6g/t Au, 0.4% Cu, 8.4g/t Ag & 0.8% Zn) from 13.0m;
including:
9.4m @ 1.9g/t AuEq (1.3g/t Au, 0.6% Cu, 15.1g/t Ag & 0.5% Zn) from 13.0m, and 5.6m @ 1.7g/t AuEq (0.9g/t Au, 0.4% Cu, 10.8g/t Ag & 1.4% Zn) from 29.7m.
Drilling further to the east confirmed shallow mineralization both within the historical resource envelope aligned with expectations (CD-378, CD-382), and mineralization to the south of the projected resource envelope, below historical surface trenching of BP Minerals (CD-372):
CD-372 20.0m @ 0.7g/t AuEq(0.2g/t Au, 0.2% Cu, 8.9g/t Ag & 0.3% Zn) from 0.0m;
including:
7.6m @ 1.2 g/t AuEq (0.4g/t Au, 0.6% Cu, 5.4g/t Ag & 0.5% Zn) from 0.0m; 4.9m @ 0.8g/t AuEq(0.1g/t Au, 0.2% Cu, 6.7g/t Ag & 1.3% Zn) from 31.4m; CD-378: 5.9m @ 5.5g/t AuEq(1.9g/t Au, 1.3% Cu, 33.5g/t Ag & 5.6% Zn) from 38.3m; and CD-382: 8.4m @ 1.3g/t AuEq(0.5g/t Au, 0.3% Cu, 12.6g/t Ag & 1.3% Zn) from 41.0m.
The growing confidence in the data combined with historical compilations has allowed the Company to nominate the Exploration Target for the Santa Helena Deposit. The Company aims to continue the program with the objective of defining a Mineral Resource, and we look forward to further results.