Sydney, Australia--(Newsfile Corp. - July 23, 2024) - Established gold producer Austral Gold Limited's (ASX: AGD) (TSXV: AGLD) (OTCQB: AGLDF) (Austral, AGL or the Company) is pleased to announce the filing on SEDAR+ and the ASX of a Technical Report, prepared in accordance with National Instrument 43-101 and Joint Ore Reserves Committee Code (JORC 2012), on the Casposo-Manantiales Mine Complex, dated 19 July 2024 (with an effective date of 30 April 2024).
Highlights of the Technical Report were disclosed in the Company's announcement dated 17 July 2024. The Technical Report is available on the Company's website at www.australgold.com and has been filed on SEDAR+ under the Company's profile at www.sedarplus.ca and on the ASX at www.asx.com.au. The Company confirms that the material highlights of the Technical Report as disclosed in the Company's announcement dated 17 July 2024 remains unchanged.
In addition, the Company wishes to provide further information as an addendum for the purposes of ASX Listing Rule 5.8.1 (set out below) and an updated JORC Table 1 (to its 17 July 2024) which inadvertently did not include sections 1 and 2, which is attached to this release.
COMPETENT PERSON'S STATEMENT
For the purposes of Listing Rule 5.22, the Company confirms that the updated Mineral Resource estimate for the Casposo Mine was based on work reviewed or compiled by Marcos Valencia, an independent "Qualified Person" as defined by NI 43-101 and a "Competent Person" as defined in the JORC (2012) Code, either as a Member of the Australian Institute of Geoscientists, or members in good standing of Recognised Professional Organisations in Canada and the United States.
The Competent Person is a consultant of Wampeso Holdings Inc.
The Competent Person consents to the inclusion in this announcement of the matters based on his information in the form and context in which it appears.
The Competent Person has sufficient experience which is relevant to the style of mineralisation and types of deposits under consideration and to the activities undertaken to qualify as a Competent Person as defined in the JORC (2012) Code.
Further information provided for the purposes of ASX Listing Rule 5.8.1 (to be read together with the release on 17 July 2024)
Geology and Geological Interpretation
The deposits exposed in the Casposo-Manantiales Property are typical Epithermal Low Sulphidation and they are multi-stage, open space filling events resulting in mineralized veins, breccias, stockworks and or veinlets.
This deposit type is characterized by quartz veins, hydrothermal breccia, stockworks, and veinlets units that contain gold, silver, electrum, and variable silver and iron sulphides. Alteration has been identified by Terraspec spectrometry and is typical of the Low-Sulphidation model, with broad haloes of white mica and less common kaolinite alteration around the mineralized veins, see figure 8.1.1 showing haloes formed around the mineralised structures. Silicification is the most common alteration type with multiple generations of quartz and chalcedony, which are typically accompanied by adularia and calcite. Pervasive silicification in the vein envelope is flanked by sericite-Illite-kaolinite assemblages. Kaolinite Illite-montmorillonite ± smectite (intermediate argillic alteration) can form adjacent to veins; kaolinite-alunite (advanced argillic alteration) may form along the tops of mineralised zones. Propylitic alteration dominates at depth and along the deposit margins.
Four main deposits have been geologically modelled by the team of the Casposo Mine. These structures are Manantiales, Mercado, Julieta and B-Vein and subsequently geostatistic was performed to determine the metal contents.
The mineralization frame occurs along a 10 km long WNW-ESE structural corridor. All the structures are the continuity of the main and previously exploited deposits called Kamila and from south to the north are B-Vein, Mercado, Julieta and Manantiales. Casposo Mine is a prolific district where the mineralisation is still open and further exploration works will help to advance several targets identified by the AGL Exploration team.
Stockpiles: No geological models were constructed for the heaps' Mineral Resource estimate, as they are artificial deposits.
Sampling and Sub-Sampling Techniques
Sampling of core drilling was performed under geological criteria in which geological and geotechnical logging was performed on the core. The former was carried out by geologists for lithological, structural and mineralogical information, while the latter was done by trained personnel for recovery and RQD information.
Core recoveries were consistently high, averaging over 90%. Mineralized intervals were selected for assaying for gold and silver content. In cases where the holes were aimed for a specific target, sampling is carried out only in selected intervals of geological interest (veins, veinlets or stockworks), as well as in the adjacent footwall and hanging-wall host rock.
Sub-sampling interval size varies from a minimum of 0.3 meter to a maximum of 1.0 meters.
Diamond Saw half core splitting was conducted on HQ and NQ core holes.
Digital photographs were taken of the core to keep a permanent record. Intervals that were not assayed are in storage at the mine site.
Historic drill hole collars were surveyed with industry standard equipment, total station or Differential GPS survey instruments by internal personnel or third-party contractors. Austral Gold undertook numerous random field checks on historic collar locations. Historic collar locations were generally found to be within ±0.5m of the expected position in the chosen datum.
The database of historical data was validated and compiled by the AGL geology department and reviewed by an Argentina based Database administrator who reconciled a representative amount of available hardcopy drill logs and assay results against the digital drill hole database.
Drilling Techniques
The Mineral Resource Estimate (MRE) was based on significant historical drilling data undertaken and collected by previous owners including Battle Mountain, Newmont, Intrepid and Troy, plus drilling conducted by AGL.
Sampling was comprised of Diamond Drilling, Reverse Circulation (RC), and Surface and Underground channels, all of which were included in the MRE.
Approximately 95% of the information was obtained from DDH (Diamond Drill Hole) type drill holes, providing a solid foundation for the MRE totaling 122,290 meters (m). Total meters drilled were 125,242 m including 2,952 m of RC drilling.
All the drilling procedures adhered to the industry standards defined by the CIM (Canadian Institute of Mining, Metallurgy, and Petroleum).
Classification
In general, classification of Mineral Resources at Casposo uses criteria based on the risk associated with the distribution of the information as follows:
Confidence in the Au and Ag estimate.
Reasonable prospects for eventual economic extraction.
Assessment of confidence in the estimate of grades included guidelines as outlined in NI 43-101:
Drill data quality and quantity.
Geological interpretation and mineralised domaining.
The spatial continuity of mineralisation.
Quantitative criteria relating to these guidelines include data density and the kriging search distances used.
More interpretative criteria include the extent of mine depletion and to a lesser extent the rock weathering condition and in situ bulk density of the mineralised and waste material.
While Austral Gold have undertaken recent industry standard quality-controlled diamond drilling, the majority of this MRE has been based on drilling data following industry standard documentation of QA/QC protocols, drilling and sampling methodologies and assay determination methods.
The overall confidence in the geological and mineralised interpretation and domaining is considered high, due in part to the existing mine openings and surface mapping undertaken by AGL employees.
The spatial continuity of mineralisation consistently demonstrated validity and geostatistical coherence across all geological and stationary domains.
The risk assessment was properly addressed using several sources of information to configure a drill grid pattern that can assure a risk level, which aligns with AGL's expectations.
A benchmarking study was carried out to compare similar Epithermal Low Sulphidation deposits in well-known mines like El Peñon, Cerro Bayo and Amancaya in Chile, Cerro Vanguardia, some structures in Cerro Moro and Cerro Negro in Argentina, and Mercedes in Mexico. Most cases are between 20 m to 35 m arrangement and the variability of the gold and silver distributions are key to defining a minor or major drill pattern.
Key information was the pattern that was used in the past by AGL and previous owners of the Casposo Mine. As stated by the AGL geology team, reliable reconciliations were obtained when was used a 25 m drill hole pattern to declare and define a resource as indicated.
Finally, this information, the benchmarking inputs and the expert criteria of the Qualified Person were relevant to define the same drill grid pattern 25 m x 25 m to define indicated resources for Manantiales, Julieta, Mercado and B-Vein deposits.
Formal studies of the optimal grid distance are strongly recommended to develop these new deposits in the Casposo Mine. The main goal is to determine the optimal distance between drill holes to ensure the desired level of confidence and minimize error for a year of ore production which AGL expects to be approximately 400Kton/year.
Low-Grade Stockpiles were classified as Indicated according to their origin, operational control process, mass determination and sampling.
Sample Analysis Method
All the respective drill and channel samples were analyzed at the Casposo Mine assay laboratory located at the mine site. The Casposo laboratory lab contains all the facilities for sample preparation, fire, wet and atomic absorption assays, as well as offices, washrooms, reagents and general storage.
The sample preparation and assay procedures for the historic data comprised:
Each drill and/or channel sample was identified with a unique sample number that is tracked throughout the assaying process. The as-received samples follow the next process of preparation:
Assaying was done by fire assaying methods (30 g charge) with a gravimetric finish. Each sample was fire-assayed using a traditional lead oxide flux as well as a known addition of silver, called in inquart. The samples are placed in gas fired assay furnaces. The fusion of the flux and inquarted sample produces a molten mixture that is poured into conical molds and cooled. The lead button formed during the fusion process is separated from the cooled slag and pounded to remove any adhering slag. The lead button is then cupelled using a magnesium oxide cupel. The remaining doré bead is flattened and weighed. The weighed doré is placed in a test tube and concentrated nitric acid added. The button is then rinsed, ammonia added, and rinsed again. The button is dried and then roasted for 5 minutes. After cooling, the gold is weighed, and gold to silver ratios are checked. If the ratio is greater than 0.40 additional silver and lead is added, and the sample is re-analyzed.
The gold and silver present in the sample are expressed according to the following formula:
External Laboratory: The AGL drill core was generated, collected and the core was analyzed by the independent and certified ALEX STEWART International, Mendoza, Argentina. The sample preparation and assay procedure for the analysis comprised:
Senior AGL field technicians frequently visited and reviewed the drilling process and transport of the core from the hole collar to the Casposo mine logging and sampling facility. All core and samples were maintained in the enclosed and locked logging facility from where batches of bagged half core samples were subsequently transported to San Juan by vehicle directly to the ALEX STEWART Laboratory in Mendoza.
Each drill sample was identified with a unique sample number.
Gold analysis: The samples were assayed by method Fire Assay Fusion, AAS Finish by ALEX STEWART Laboratories Mendoza, Argentina in which sample decomposition by Fire Assay Fusion in which a 30g sample is fused with a mixture of lead oxide, sodium carbonate, borax, silica and other reagents as required, and inquarted with 6 mg of gold-free silver and then cupelled to yield a precious metal bead.
The bead is then digested in 0.5 mL dilute nitric acid in a microwave oven, 0.5 mL concentrated hydrochloric acid is then added, and the bead is further digested in the microwave at a lower power setting. The digested solution is cooled, diluted to a total volume of 4 mL with de- mineralized water, and analyzed by atomic absorption spectroscopy against matrix-matched standards (lower limit of 0.01 g/t Au and upper Limit 10 g/t Au).
For samples > 10 g/t Au and < 1000 g/t Au the method was implemented using Fire Assay Fusion sample decomposition and gravimetric analysis whereby a prepared 30 g sample is fused with a mixture of lead oxide, sodium carbonate, borax, silica and other reagents in order to produce a lead button. The lead button containing the precious metals is cupelled to remove the lead. The remaining gold and silver bead are parted in dilute nitric acid, annealed and weighed as gold.
Silver analysis: The sample is assayed by ALEX STEWART Laboratories Mendoza, Argentina in which sample decomposition is via HNO3-HClO4-HF-HCl digestion (ASY 4ACID) and analysis by AAS.
The method involves the preparation of a (0.4) g sample combined with nitric, perchloric, and hydrofluoric acids, and then evaporated to dry. Hydrochloric acid is added for further digestion, and the sample is dried again. The residue is dissolved in nitric and hydrochloric acids and transferred to a volumetric flask (100 or 250) mL. The resulting solution is diluted to volume with de-mineralized water, mixed and then analyzed by atomic absorption spectrometry against matrix-matched standards (lower limit of 2 g/t Ag and upper Limit 200 g/t Ag).
For samples between >200 g/t Ag and < 10,000 g/t Ag the method was implemented using Fire Assay Fusion sample decomposition and gravimetric analysis whereby a prepared 30g sample is fused with a mixture of lead oxide, sodium carbonate, borax, silica and other reagents in order to produce a lead button. The lead button containing the precious metals is cupelled to remove the lead. The remaining gold and silver bead are parted in dilute nitric acid, annealed and weighed as gold. Silver is then determined by the difference in weights.
Quality Assurance and Quality Control
A proper QAQC program was implemented by AGL following the industry standards defined by the CIM.
Internal Laboratory
Several CRM were implemented like standards, blanks and duplicates.
For the drill hole data, an internal quality control program was implemented by AGL which comprised:
Duplicate assay pulps on 5% of volume;
Duplicate assay splits on 5% of volume; and
Standards inserted every 20th sample.
AGL utilized two mineral standards for the drilling:
For the AGL infill drilling diamond core and Channel Sampling analysis results were obtained for standards and blanks. Accuracy is monitored by certified standards which have an accepted value plus 2 standard deviations. Additionally, precision is monitored within a percentile relative variation range of 2 standard deviations.
External Laboratory
Several CRM were implemented like standards, blanks and duplicates.
For the AGL diamond drill core, quality control procedures adopted include the insertion of a range of certified geochemical standards and blanks that were inserted methodically on a one for every 20- sample basis (5%).
AGL utilized ten mineral standards for the drilling:
Oreas 251b: Au: 0.51 ± 0.017 Ag: 0.1 ± 0.017
Oreas 607: Au: 0.67 ± 0.024 Ag: 5.9 ± 0.189
Oreas 601c: Au: 0.97 ± 0.048 Ag: 50.3 ± 2.31
Oreas 624: Au: 1.16 ± 0.053 Ag: 45.3 ± 1.26
Oreas 603c: Au: 4.96 ± 0.186 Ag: 294 ± 13
Oreas 609c: Au: 4.97 ± 0.260 Ag: 24.6 ± 1.03
Oreas 610: Au: 9.83 ± 0.254 Ag: 49.4 ± 1.79
Rock Labs SP49: Au: 18.34 ± 0.34 Ag: 60.2 ± 2.5
Rock Labs SP47: Au: 39.88 ± 0.85 Ag: 122.3 ± 5.7
Rock Labs OxQ75: Au: 50.3 ± 1.100 Ag: 153.9 ± 7.3
For the AGL diamond drill core, RC drilling and Channel Sampling analysis were conducted for the results for the standards and blanks. Accuracy is monitored by certified standards which have an accepted value plus 2 standard deviations and additionally precision is monitored in a percentile relative variation range within 2 standard deviations.
Estimation methodology
Stationary domains were estimated for Au and Ag were made using ordinary kriging (OK) via a three- dimensional (3D) estimation methodology. The 3D method utilises regularized composites to create an additive variable.
Drilling Database
Drill hole data was provided in MS Excel format and represents a compilation of all drilling conducted by the AGL geology team. This data was imported and reviewed in a 3D Vulcan drill hole database. The main files containing the imported fields and their descriptions are found in Table 14.1.
The grid datum used for collar and survey files is Gauss Kruger, Datum Campo Inchauspe 1969 Zone 2.
The assay table contained single fields for Au and Ag. No validation or check re-assay data were available in the data supplied. However, in the central data base managed by the AGL corporate data base administrator, the information is accessible.
An additional MS Excel table was provided by Austral Gold that contains the interpreted intercepts defining the stationary domains. Given the nature of these type of deposits, they primarily consist of veins.
These interpretations can provide a basis for the interpreted domains that were used as a guide to validate the model in 3D. The database structure is a typical relational database to compile the information of the collar like coordinates and some descriptors of the project and type of drilling, the drill hole topography, the assay table record the information related to the grades and geological units and the lito table record geological information. Table 14.1 describes the tables and fields in the database. The holeid field serves as the key field to relate the tables.
Geological Modelling, Stationary Domains and Composites
Weathering Surfaces: No oxidation/weathering surfaces have been provided for the MRE.
Geological Interpretation
The mineralised domains evaluated for the MRE were interpreted by the AGL geology team using a model in Leapfrog and a set of cross vertical sections. They were used to guide the 3D modelling for veins, breccias, stockwork or veinlets mineralization domains developed in Vulcan software.
For Manantiales deposit, a 3D model was developed using 3 main geological features that are mineralized Veins or hydrothermal Breccias, for both hangingwall and footwall a body of tectonic breccia was modelled and, in some cases, can bearing low grade mineralization. Also, a final envelope that include veinlets or waste rock was modelled to constrain the internal domains of mineralization.
For the remaining ore bodies, a single domain was modelled, consisting of veins or hydrothermal breccias which contain the gold and silver mineralization. This domain was defined as the main domain and an external envelope identified as a veinlet envelope was defined to constrain the main ore body.
Table 14.2: Domain codes.
Geological Domain
Code
Vein and Hydrothermal Breccia
MQV
Hangingwall and Footwall Tectonic Breccia
BX*
Veinlet developed on the wall rock
VLT
* only developed in Manantiales Deposit
Once the modelling was finished, all the drill holes considered in the estimation were flagged in a field called flag and ug into the Assay table to mark every single sample with the corresponding stationary domain (see Table 14.2). This method is developed to use the real length of the samples when the process of compositing is developed. When the regularized composites are built, they are broken down using the physical limits of every stationary domain defined in the flag field. The regularized length choose is 0.5 m due to the high variability of the grades in the width direction and also the selected block size was0.5 m*0.5 m*0.5 m, for the main stationary domains.
When the composites are created, a regular length is selected which is related to the block size, and start in the first geological limit. Once the routine is completed, the first composite to the length is defined, and the routine will create the following until the end of the geological limit in every geological unit. It is important to note that when the routine is building the last composite, each stationary domain can create the last using a length minor or equal to the regular length defined. No compensation in length is defined in this routine. Figure 14.1 illustrates the Stationary Domains in the Casposo Low Sulfidation Epithermal Mineralization System. Grey dot lines define the VLT domain and the magenta line define the MQV domain figures 14.2, 14.3 and 14.4 shows the 3D stationary domains modeled for Manantiales, Julieta, Mercado and B-Vein.
Figure 14.1 Stationary Domains (Cross Section view) AuEq in ppm.
Composites are the information that will be used in the estimation process and statistics are performed to all the units considered. Table 14.4 shows the codes defined for the Stationary Domains for the four deposits and the Table 14.5 are the statistics performed.
Geological and Estimation Domains
The geological domains were developed based on the interpretation of the AGL geology team for each deposit. Detailed logging was performed and compiled to define the main geological units which are the main mineralized structure composed of veins or hydrothermal breccias that were coded and interpreted in every cross section. An envelope of waste rock or in some cases low grade mineralization was interpreted to constrain the main geological unit that bearing gold and silver mineralization.
To define the Estimation Domains, we relied on the geological domains as long as the structural continuity was present. Parallel, secondary or tensional structures, define different geological domains and consequently different estimation domains.
In these types of deposits, it is typical to find parallel or tensional structures in an arrangement that is known as extensional jogs or bends.
Explicit domains were defined and the main mineralized estimation domain that was called Massive Quartz Vein [MQV], outer domains were identified as Veinlet [VLT] alluding to waste and in some cases low grade estimation domain and geologically present veinlets described in the log and in some cases when the mineralization style was not described the gold and silver grade can be used to define the outer domain. Only in the case of Manantiales deposit was another domain defined as breccia [BX] identified, whereby the estimation domains formed by the tectonic breccia in both hanging wall and footwall rocks.
3D Estimation: A typical process of 3D estimation was performed in every project. Volume is defined based on the drill holes intersections for both mineralized or waste geological domain, which will be used as Estimation Domain as long as the structural 3D continuity was verified. Sampling was transformed to regular composite and used to develop the geostatistical estimation.
Domain Coding: Compositing of the drill hole assay data was carried out using the run length method, that is defined according to the features of the population analyzed. The process is explained in more detail in section 14.7. The method is controlled by the unique numeric coding within the MRE database.
Bulk Density: A comprehensive program of systematic bulk density measurement was implemented and developed by AGL, and Bulk density, a compilation of 310 samples was provided detailed by rock type and was assigned an average value for each one, were calculated using accumulated and average values which show coherent values.
For the MRE, 2.5 ton/m3 was assumed based on the information provided and defined by the mine planning department. As the mineralization styles are mainly bearing in veins, hydrothermal breccias, stockworks and veinlets, it is recommended to perform intensified measurements in the mineralized units.
Currently, the amount of information that was collected in waste units is sufficient. However, the QP recommends continuing with this program and focusing on intensifying the measurements in mineralized units rather than waste rocks. Only 7 measurements were taken in veins or any other type of mineralized rock and the author agreed with the use of a constant value of 2.5 ton/m3 for all rock types.
The project has been subject to both open pit and underground mining. Historic mining voids have been precisely quantified. Recent surface surveys undertaken by AGL have provided for all the deposits. The resulting wireframe of open pit voids is considered a reasonable representation of the base of surface mined volumes. The block models were properly built and blocks were created above the surface and declared as air.
Underground mining voids have been declared as mined-out material. For these voids, underground sampling and 3D tunnel wireframes were used to define the area exploited in each vein area.
Exploratory Data Analysis and Outliers
Complete global statistics of composite tabulations of Au, Ag on the MQV, BX and VLT Stationary Domains are presented. Tables within this section present the relevant statistics for each deposit and their respective domains.
Raw statistics for the calculated regularized 0.5 m composite are shown in Table 14.5.
Table 14.4: Stationary Domains and Codes for Manantiales, Julieta, Mercado and B-Vein Deposits.
The generally high variance characteristics and material outliers within the composite's distribution indicates the need to limit high-grade values.
Outliers can be addressed using the following actions to limit their influence:
Thresholds are detected and defined using lognormal probability plot, then its consistency of the definition is checked in the table calculating the relative differences between composites, when the relative difference is greater than 5% it could be possible to consider as an outlier. Both definitions must be geologically consistent and coherent and relevant experience in this matter is needed to define the threshold in a relevant stationary domain.
Capping means all the composites major or equal to the threshold defined will be cutting and be replaced for this value. This action is not performed for the Casposo deposits because the metal content involved can be seriously affected due to the nature of this type of deposit's high grade variability and less geological continuity.
Rather than capping, a high yield restriction is performed and is defined in the kriging plans. This means the treatment of the grades above the threshold will be restricted to an inner and smaller ellipsoid which define a very restricted and small influence, into the main search that were defined in every estimation pass and only when the samples above the top-cut or threshold is in this smaller search they will be used to estimate a block. If the outliers are out of the small and inner search never will be used to estimate a block.
Table 8-5 exhibits the threshold defined in the Stationary Domains. All distributions were analyzed and the defined thresholds were applied in the estimation plans.
Table 14.6: Outliers Definition for deposits and Stationary Domains.
The main Massive Quartz Vein (MQV) domains exhibit grade ranges and variabilities considered large for robust linear interpolation. Visual inspection clearly shows the domains consist of mineralized and non-mineralized regions. Minor structures were estimated considering a linear interpolation, although the amount of information can be small, it is enough to develop the process.
Spatial Variability
One of the main parameters to define in a resource estimation is the spatial variability and the definition of a valid function to solve the Kriging equations. Variograms provide the information to solve an equation system with a unique and valid solution.
On the other hand, for this type of deposits a proper definition of anisotropy or the way that grades are distributed in the space is key to ensure an accurate process of estimation. In the early days and due to the limitation of the estimation software was usual to use fixed directions of the search ellipsoid but now is possible to use some routines to mimic the spatial distribution of geological variables like grades called local variable anisotropy that are fully conditioned by geological constrains. In all the Casposo Deposits was used a routine of variable ellipsoid to mimic the 3D distribution of grades and avoid some artifacts.
3D Variograms were performed using operational sampling to define a function to be applied in the deposits. The aim of production channels was to obtain information about the shortest distances rather than the longest distances. A semi-empirical model is provided to use in the estimation process and provide a coherent solution related to the optimal grid drilling.
Table 14.7: Semi-variogram defined as a semi-empirical model.
Local Variable Anisotropy is an important feature of a geological domain and therefore for the stationary domain, it is important to know which are the directions of best continuity of mineralization called anisotropy. It is usual to define the local variable anisotropy to mimic the continuity of relevant geological features. In that way, was build an Anisotropy field based on the geological and stationary domains characteristics in specific the 3D orientation. Vulcan can build an Anisotropy Field based on surfaces and the information of this surface was recorded in the variables defined as bearing, plunge and dip.
Geological information is the base in the case of Epithermal Low Sulfidation deposits because they are structurally controlled and it is normal to follow a tabular shape of the ore bodies.
Cut-Off Grades and other parameters
Mineral Resources
Reasonable Prospect Assessment
The project is located on Mining Leases granted and has been historically mined. Grades and geometry are amenable to open pit and underground mining. The current (April 2024) Au price is ~US$2,250 per ounce and given probable credits from Ag, an average positive revenue per tonne (after recoveries) would be achievable. Therefore, there is no apparent reason the Casposo Au-Ag deposits could not be mined economically.
The reported open pit MRE has been confined above an optimisation shell and underground stopes modelled on the criteria tabulated in Table 14.12 and Table 14.13. The shell selected for a base of reasonable expectations for reporting the MRE assumed a gold price of USD $2,000/ounce and a silver price of USD $20/ounce.
Table 14.13: Parameters used in the optimisation process.
Mining
Cost
Type
Cut-Off Grade
Dilution
Recovery
Slope
Density
Mining
Procesing
G&A
Selling
Operating
Cash
AuEq ppm
%
%
°
ton/m3
USD/ton
USD/ton
USD/ton
USD/ton
USD/ton
USD/ton
Open Pit
1.5
-
95
50
2.5
6
65
15
38.7
71
124.7
Underground
2.0
15
93
40/140
2.5
60
65
15
38.7
125
178.7
Stockpile *
1.0
-
-
-
1.8
1.5
45
10
38.7
46.5
95.2
* only variable costs was considered
Other parameters considered in the underground optimization are as follow:
Distance between levels: 15 m [Bench 11 m, Drift 4 m]
Minimum and maximum width: Bench 2.08 to 6 and drift 4 to 6
Minimum and maximum dip: Bench 40° and drift 140° Metallurgical Recoveries were used according to the information obtained on the deposit to optimize the open pit and underground method. Table 14.13 illustrates the recoveries in each deposit.
Table 14.14: Recoveries used in the optimisation process.
Stockpile optimization uses nearly the same parameters as open pit optimization. The key differences lie in the mining and general administrative costs, that were considered as variable costs.
Mineral Reserves
No Mineral Reserve were estimated.
Mining and Metallurgical Methods and Parameters
No mining methods were defined and metallurgical methods and parameters were assumed only to develop a reasonable prospect for economic extraction.
About Austral Gold
Austral Gold is a growing gold and silver mining producer building a portfolio of quality assets in the Americas. Austral continues to lay the foundation for its growth strategy by advancing its attractive portfolio of producing and exploration assets. For more information, please visit the Company's website at www.australgold.com.
Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.
Release approved by the Chief Executive Officer of Austral Gold, Stabro Kasaneva.
Statements in this news release that are not historical facts are forward-looking statements. Forward-Looking statements are statements that are not historical, and consist primarily of projections - statements regarding future plans, expectations and developments. Words such as "expects", "intends", "plans", "may", "could", "potential", "should", "anticipates", "likely", "believes" and words of similar import tend to identify forward- looking statements. Forward-Looking statements in this news release include Austral continues to lay the foundation for its growth strategy by advancing its attractive portfolio of producing and exploration assets.
All of these forward-looking statements are subject to a variety of known and unknown risks, uncertainties and other factors that could cause actual events or results to differ from those expressed or implied, including, without limitation, uncertainty of exploration programs, development plans and cost estimates, commodity price fluctuations; political or economic instability and regulatory changes; currency fluctuations, the state of the capital markets especially in light of the effects of the novel coronavirus, uncertainty in the measurement of mineral resources and reserves and other risks and hazards related to the exploration of a mineral property, and the availability of capital. You are cautioned that the foregoing list is not exhaustive of all factors and assumptions which may have been used. Austral cannot assure you that actual events, performance or results will be consistent with these forward-looking statements, and management's assumptions may prove to be incorrect. Austral's forward-looking statements reflect current expectations regarding future events and operating performance and speak only as of the date hereof and Austral does not assume any obligation to update forward-looking statements if circumstances or management's beliefs, expectations or opinions should change other than as required by applicable law. For the reasons set forth above, you should not place undue reliance on forward-looking statements.
JORC Code, 2012 Edition - Table 1 report
Section 1 Sampling Techniques and Data
(Criteria in this section apply to all succeeding sections.)
Criteria
JORC Code explanation
Commentary
Sampling techniques
Nature and quality of sampling (eg cut channels, random chips, or specific specialised industry standard measurement tools appropriate to the minerals under investigation, such as down hole gamma sondes, or handheld XRF instruments, etc). These examples should not be taken as limiting the broad meaning of sampling.
Include reference to measures taken to ensure sample representivity and the appropriate calibration of any measurement tools or systems used.
Aspects of the determination of mineralisation that are Material to the Public Report.
In cases where 'industry standard' work has been done this would be relatively simple (eg 'reverse circulation drilling was used to obtain 1 m samples from which 3 kg was pulverised to produce a 30 g charge for fire assay'). In other cases more explanation may be required, such as where there is coarse gold that has inherent sampling problems. Unusual commodities or mineralisation types (eg submarine nodules) may warrant disclosure of detailed information.
Diamond core (HQ and NQ) was cut longitudinally on site using a diamond saw. Samples lengths are generally from 0.3 m to 1.0 m in length. Sample lengths are selected according to lithology, alteration, and mineralization contacts.
Channel samples are cut into surface outcrop using a hand-held diamond edged cutting tool. Parallel saw cuts 3-5cm apart are cut 2-4cm deep into the rock which allows for the extraction of a representative sample using a hammer and chisel. The sample is collected onto a plastic mat and collected into a sample bag.
Core and channel samples were prepared by drying, crushing to 10 mesh (≥80%), quartering (600g), and pulverizing to 106 microns (≥95%). A 50g charge was analyzed for Au by fire assay with AA determination. Where the fire assay grade is > 10 g/t gold, a 50g charge was analyzed for Au by Fire assay with gravimetric determination.
A 10g charge was analyzed for 39 elements by using dissolution of 0.2g in aqua regia (partial digestion for some elements, especially Al, Ba, Cr, K, Na, Sn, Sr, Ta, Ti, V, and W) and determination by Radial ICP-OES.
For Ag > 100 g/ overlimit analysis was done by the same method using a different calibration.
Unused pulps are returned from the laboratory to the Project and stored in a secure location, so they are available for any further analysis. The remaining drill core is stored undercover for future use if required.
Drilling techniques
Drill type (eg core, reverse circulation, open-hole hammer, rotary air blast, auger, Bangka, sonic, etc) and details (eg core diameter, triple or standard tube, depth of diamond tails, face-sampling bit or other type, whether core is oriented and if so, by what method, etc).
AGL drilling was exclusively conducted using Diamond Drilling (DD). Historic drilling was conducted by previous explorers, who also used DDH. Truck mounted and hand portable rigs were operated by various drilling contractors from San Juan and Mendoza. There is information available on oriented core by previous explorers, which was done by using HQ3 core (triple tube) and ballmark.
Core details for DDH drill holes and channels completed in the project that are used in the resource estimate are shown below in GK Campo Inchauspe, Faja 2 projection. Collar locations for drill holes are surveyed using DGPS.
Drill sample recovery
Method of recording and assessing core and chip sample recoveries and results assessed.
Measures taken to maximise sample recovery and ensure representative nature of the samples.
Whether a relationship exists between sample recovery and grade and whether sample bias may have occurred due to preferential loss/gain of fine/coarse material.
Drill core is placed into wooden boxes by the drillers and depth marks are indicated on wooden blocks at the end of each run. These depths are reconciled by AGD geologists when measuring core recovery and assessing core loss. Triple tube drilling has been being done by AGD to maximise core recovery.
Channel samples have been weighed to ensure a consistency between sample lengths and weights. The channel samples are collected from saw-cut channels and the whole sample is collected for analysis. There is no correlation between sample length and assay values.
Logging
Whether core and chip samples have been geologically and geotechnically logged to a level of detail to support appropriate Mineral Resource estimation, mining studies and metallurgical studies.
Whether logging is qualitative or quantitative in nature. Core (or costean, channel, etc) photography.
The total length and percentage of the relevant intersections logged.
For AGL drilling, all core is photographed and logged for recovery, RQD, weathering, lithology, alteration, mineralization, and structure to a level that is suitable for geological modelling and Mineral Resource Estimation.
Geological logging was conducted using GV Mapper, in a format that can readily be cross-checked and is backed-up and transferred to a secure, offsite, cloud-based database which holds all drill hole logging sample and assay data.
No specialist geotechnical logging has been undertaken by AGD.
Detail logs, core and photographs are available for all historical drilling. Previous explorers conducted detailed geotechnical logging and reporting.
Sub-sampling techniques and sample preparation
If core, whether cut or sawn and whether quarter, half or all core taken.
If non-core, whether riffled, tube sampled, rotary split, etc and whether sampled wet or dry.
For all sample types, the nature, quality and appropriateness of the sample preparation technique.
Quality control procedures adopted for all sub-sampling stages to maximise representivity of samples.
Measures taken to ensure that the sampling is representative of the in situ material collected, including for instance results for field duplicate/second-half sampling.
Whether sample sizes are appropriate to the grain size of the material being sampled.
AGL samples have been submitted to the Alex Stewart International Argentina laboratory in Mendoza, Argentina. The sample preparation technique is considered appropriate for the style of mineralization present in the Casposo-Manantiales Mine Complex.
Sample sizes are appropriate for the mineralisation style and grain size of the deposit.
Sample intervals are selected based on lithology, alteration, and mineralisation boundaries.
Representative samples of all of the core are selected. Second- half core or quarter core samples have been submitted for quality control. The second half of the core samples has been retained in the core trays for future reference.
Drill core is cut longitudinally using a diamond saw for sampling of ½ the core. The geologist logging the core, marks where the saw cut or split is to be made to ensure half-core sample representativity.
Quality of assay data and laboratory tests
The nature, quality and appropriateness of the assaying and laboratory procedures used and whether the technique is considered partial or total.
For geophysical tools, spectrometers, handheld XRF instruments, etc, the parameters used in determining the analysis including instrument make and model, reading times, calibrations factors applied and their derivation, etc.
Nature of quality control procedures adopted (eg standards, blanks, duplicates, external laboratory checks) and whether acceptable levels of accuracy (ie lack of bias) and precision have been established.
A proper QAQC program was implemented by AGL following the industrial standards defined by the CIM.
Internal Laboratory: several CRM were implemented like standards, blanks and duplicates. For the drill hole data, an internal quality control program was implemented by AGL which comprised:
Duplicate assay pulps on 5% of volume;
Duplicate assay splits on 5% of volume; and
Standards inserted every 20th sample.
AGL utilized two mineral standards for the drilling:
For the Austral Gold infill drilling, diamond core, and Channel Sampling analysis were conducted for the results using the standards and blanks. Accuracy is monitored by certified standards which have an accepted value plus 2 standard deviations and additionally precision is monitored in a percentilerelative variation range within 2 standard deviations.
External Laboratory: several CRM were implemented like standards, blanks and duplicates.
For the Austral Gold diamond drill core, quality control procedures adopted include the insertion of a range of certified geochemical standards and blanks that were inserted methodically on a one for every 20-sample basis (5%).
For the Austral Gold diamond drill core, RC drilling and Channel Sampling analysis were conducted on the results for the standards and blanks. Accuracy is monitored by certified standards which have an accepted value plus 2 standard deviations and additionally precision is monitored in a percentile relative variation range within 2 standard deviations.
Verification of sampling and assaying
The verification of significant intersections by either independent or alternative company personnel.
The use of twinned holes.
Documentation of primary data, data entry procedures, data verification, data storage (physical and electronic) protocols.
Discuss any adjustment to assay data.
All information contained in this technical report was generated by AGL, most of which was previously verified in the technical report prepared in 2016 by RPA and all information developed in Manantiales after this date has been reviewed and validated by the QP. All information has been reviewed by the author and is declared to be in accordance with the guidelines established by the CIM and falls under the requirements of JORC Code for publication to the market.
Verification was carried out by taking the original information, comparing it with what was reported in the 2016 report, and also reviewing the procedures that AGL applied during its drilling and quality assurance activities.
All information is captured, and processing procedures and protocols have been developed to detect deviations in the early stages of the process and to apply corrective measures for mitigation and to minimize the sources of risk of failures in the information generated and declared as public.
Location of data points
Accuracy and quality of surveys used to locate drill holes (collar and down-hole surveys), trenches, mine workings and other locations used in Mineral Resource estimation.
Specification of the grid system used.
Quality and adequacy of topographic control.
Following completion of drilling, collars are marked and surveyed using a differential GPS (DGPS) relative to a nearby Argentinian SGM survey point. The collars have been surveyed in Campo Inchauspe zone 2.
The drill hole collars were surveyed with the proper survey instrument. All Austral Gold drill holes were downhole surveyed in a continuous down hole trace format using single-shot and lately Reflex-EZTrack and sometimes gyroscope.
Following completion of the channel sampling, the location of the channel samples is surveyed from a survey mark at the entrance to the underground workings, located using differential GPS. The locations have been surveyed in Campo Inchauspe zone 2.
The drill rig is set-up on the drill pad using hand-held survey equipment according to the proposed hole design.
Data spacing and distribution
Data spacing for reporting of Exploration Results.
Whether the data spacing and distribution is sufficient to establish the degree of geological and grade continuity appropriate for the Mineral Resource and Ore Reserve estimation procedure(s) and classifications applied.
Whether sample compositing has been applied.
Data distribution for exploration purpose is separated by approximately 50 to 75 meters.
Delineation drill spacing has been designed to intersect the mineralization to a nominal 25x25 meters to define indicated resources for Manantiales, Julieta, Mercado, B-Vein, and Inca deposits.
Spacing and distribution is currently enough to support a Mineral Resource Estimate under the Indicated and Inferred categories.
A small proportion of the mineral resources were classified as Measured based on the physical exposure of the structure and the density of channel sampling.
Sample compositing has been done within the mineralization boundaries. Samples were composited to 0.5 meter for grade estimation purposes.
Orientation of data in relation to geological structure
Whether the orientation of sampling achieves unbiased sampling of possible structures and the extent to which this is known, considering the deposit type.
If the relationship between the drilling orientation and the orientation of key mineralised structures is considered to have introduced a sampling bias, this should be assessed and reported if material.
As far as is currently understood and where practicable, the orientation of sampling achieves unbiased sampling of structures and geology controlling the mineralisation.
For channel sampling, the orientation of the sample is determined by the orientation of the outcropping veins and breccias.
Drilling and channel sampling has been designed to provide an unbiased sample of the geology and mineralisation targeted.
Sample security
The measures taken to ensure sample security.
Samples were under constant supervision by site security, senior technical personnel and courier contractors prior to delivery to the preparation laboratories in San Juan and Mendoza.
Standard QAQC procedures were implemented and currently applied. Chain of custody is reliable and the internal and external laboratories are constantly monitored.
Gold and silver values are provided by the laboratories in pdf and excel format files and imported into the geological data base system.
Audits or reviews
The results of any audits or reviews of sampling techniques and data.
There has not yet been any independent reviews of the sampling techniques and data.
Analytical laboratories for the project have not been inspected at this stage.
Section 2 Reporting of Exploration Results
(Criteria listed in the preceding section also apply to this section.)
Criteria
JORC Code explanation
Commentary
Mineral tenement and land tenure status
Type, reference name/number, location and ownership including agreements or material issues with third parties such as joint ventures, partnerships, overriding royalties, native title interests, historical sites, wilderness or national park and environmental settings.
The security of the tenure held at the time of reporting along with any known impediments to obtaining a licence to operate in the area.
The Casposo property is located in the Calingasta Department, San Juan Province, Argentina, at approximately 69°36'W longitude and 31°12'S latitude and centered coordinate 6,548,000 N and 2,438,000 E. The Casposo property is situated approximately 150 km west of San Juan, the capital of San Juan Province, Argentina, approximately 25 km north west of the town of Calingasta (Figure 4-1). The commune of Calingasta hosts a population of approximately 8,500 people based on the 2010 census for which its main economic activities have been historically agriculture, tourism and mining and the Casposo Mine was operated between 2010-2019. The Casposo Project is widely recognised and valued throughout the local community as a major source of jobs and commerce by employment during full operation of approximately 450 direct jobs and for which approximately 80% of the employees were historically resident in Calingasta.
The Casposo Property area is located within mining claims held by the Casposo Argentina Mining Ltd., which is 100% owned by the Austral Gold Limited group of companies. The Casposo- Manantiales claim block is comprised of 25 mining claims which cover an area of 48,611 hectares.
Two mining claims packages comprise the property Casposo Mine site. The southern and eastern claims are fully controlled by AGL (yellow in Figure 3-2.1) and the northern and western is an agreement between AGL and IPEEM (a provincial institute in charge of mining and development) (magenta in Figure 3-2.1) which agreed that the operator would be AGL and IPPEM would receive a 1% royalty on sales for the duration of the agreement for 5 years, and 5 phases of exploration investment totalling USD 1.5 million.
File No. Name Date Area (ha) Notes 520-0438-M-1998 Mine Lease Kamila Dec. 19, 2005 3,487.9 Granted 4141348-I-2005 Mine Lease Julieta Apr. 26, 2007 2,600.0 Survey pending 11240189-I-2007 Mine Lease Alicia 1 Apr. 8, 2009 15.9 Survey pending 11240190-I-2007 M de D Maria Jose Mar. 3, 2009 3,985.4 Application 11240191-I-2007 M de D Vallecito Mar. 11, 2015 789.0 Recorded 1124-59-T-2011 M de D Maria Paz Feb. 23, 2011 400.0 Application 1124-62-T-2011 M de D Carolina Feb. 23, 2011 2,251.0 Application 1124-64-T-2011 M de D Maria Luz Feb. 23, 2011 2,000.0 Application 1124-225-T-2013 M de D Paloma Jun. 10, 2013 2,167.2 Application 1124-226-T-2013 M de D Julia Jun. 10, 2013 2,326.1 Application 1124-220-T-2014 M de D Alina Jun. 24, 2014 2,488.8 Recorded 425315-C-2002 Exp. Casposo NE Aug. 11,2003 1,591.6 Ch & R * 425120-C-2003 Exp. Casposo Este Aug. 2, 2003 2,211.2 Charted 414299-I-2004 Exp. Altos de Manrique Aug. 27, 2004 1,839.4 Charted 414375-I-2004 Exp. Timbirimbas Nov. 10, 2008 3,498.9 Charted 414501-I-2004 Exp. Sara 1 May 12, 2014 277.0 Ch & R * 414501-I-2004 Exp. Sara 4 Sep. 22, 2009 3,306.9 Ch & R * 414717-I-2004 Exp. Carmen Alto Oct. 5, 2011 1,384.7 Charted 1124-350-I-2007 Exp. Rosalia Oct. 6, 2014 1,725.5 Charted 1124-346-I-2009 Quarry Retamas 1 Apr. 12, 2012 0.7 Charted 1124-393-T-2010 Quarry Guadalupe Aug. 4, 2010 0.9 Charted 1124-284-T-2013 Quarry Beatriz 1 Mar. 21,2014 4.2 Charted 520-0120-M-97 Manantial 3 1997 3,125.7 Granted 520-0121-M-97 Manantial 4 1997 3,072.6 Granted 520-0122-M-97 Manantial 5 1997 3,061.2 Granted
Total (25 mining rights) 48,611.8 * Chartered and Recorded
The mining claims are in good standing and the applicable annual fees were paid in January 2024.
Exploration done by other parties
Acknowledgment and appraisal of exploration by other parties.
First records of historical exploration traces back to 1997, when Manantiales S.A., a local company, applied for new mining tenements to cover the original terms of the H. Bastias tenements.
Between 1998 and 2002, gold and silver mineralization was discovered in the Casposo District. Battle Mountain and Newmont Mining Limited discovered gold and silver mineralization through regional exploration activities, including surface sampling, geological mapping, trenching, rock sampling, geophysics and drilling holes.
Subsequently, intrepid Minerals Corporation invested in various initiatives from 2002 to 2009 to advance the project. These efforts include regional reconnaissance, detailed trench sampling, core re-logging, bulk sampling for metallurgical studies and the development of diamond drill holes.
In 2009, Troy Resources Argentina assumed control and continued development studies. Commercial production started in November 2010 and concluded in 2015, resulting in total production of 283,000 ounces of gold (Au) Oz and 9.5 million ounces of silver (Ag).
In 2016, Austral Gold Limited purchased a 51% interest in Troy Resources Argentina (later renamed Casposo Argentina Mining Limited) AGL subsequently acquired an additional 19% in 2017 and the remaining 30% in 2019. As the mine operator, AGL restarted operations in 2016 and produced approximately 98,000 gold equivalent ounces including 44,000 gold ounces and 4.1 million silver ounces until the mine was placed on care and maintenance in 2019.
Currently the project is under study for reopening and this MRE is a crucial component of the ongoing assessment.
Geology
Deposit type, geological setting and style of mineralisation.
The Casposo District is situated within the Cordillera Principal which runs along the border between Argentina and Chile approximately 1,500 km in a volcanic and seismic active zone. Basement is formed by Permian-Triassic rocks characterized by calk-alkaline affinity intrusive and volcanic rocks of andesitic to rhyolitic composition regionally known as Choiyoi Group. These younger Jurassic-Cretaceous sediments were thickened by compression and trusting since the Late Cretaceous in a thin- skinned fold trust belt.
In the Mine area, the Cordillera Frontal is underlain by marine metasediments (shales, sandstones, and conglomerates) of La Puerta Formation (Carboniferous-Lower Permian). It correlates with the Agua Negra Formation to the north.
The Casposo gold-silver mineralization occurs in both the rhyolite and underlying andesite, where it is associated with banded quartz-chalcedony veins, typical of Low Sulphidation Epithermal environments. Adularia in the main veins gives an age date of 280 ± 0.8 Ma (K/Ar), very close to the published age dates for the andesite unit. Post-mineralization dykes, of rhyolitic, aphanitic-felsic and trachytic compositions which affects all the deposits Manantiales, Julieta, Mercado and B-Vein often cut the vein systems. These dykes, sometimes reaching up to 30 m thickness, are usually steeply dipping and north-south oriented. The mineralization at Casposo is typical of a low sulfidation type and is interpreted to be of a multi-stage, open space filling epithermal origin resulting in mineralized veins, hydrothermal breccias, stockworks or veinlets.
The deposits exposed in Casposo Property are typical Epithermal Low Sulphidation (LS) and they are multi-stage, open space filling events resulting in mineralized veins, breccias, stockworks and or veinlets.
This deposit type is characterized by quartz veins, hydrothermal breccia, stockworks, and veinlets units that contain gold, silver, electrum, and variable silver and iron sulphides. Alteration has been identified and silicification is the most common alteration type with multiple generations of quartz and chalcedony, which are typically accompanied by adularia and calcite. Pervasive silicification in the vein envelope is flanked by sericite-Illite- kaolinite assemblages. Kaolinite Illite-montmorillonite ± smectite (intermediate argillic alteration) can form adjacent to veins; kaolinite-alunite (advanced argillic alteration) may form along the tops of mineralised zones.
The mineralization framework extends along 10 km long NW-SE structural corridor. All the structures considered in this Technical report are continuations of the main and previously exploited deposits known as Kamila. Moving from south to north, these structures include B-Vein, Mercado, Julieta, Manantiales and Inca. The Casposo Property is a prolific district where mineralisation remains open and further exploration efforts will contribute to advance several targets identified by the AGL Exploration team.
Drill hole Information
A summary of all information material to the understanding of the exploration results including a tabulation of the following information for all Material drill holes:
easting and northing of the drill hole collar
elevation or RL (Reduced Level - elevation above sea level in metres) of the drill hole collar
dip and azimuth of the hole
down hole length and interception depth
hole length.
If the exclusion of this information is justified on the basis that the information is not Material and this exclusion does not detract from the understanding of the report, the Competent Person should clearly explain why this is the case.
The MRE was based on significant historical drilling and data undertaken and collected by previous owners including local Battle Mountain and Newmont, Intrepid and Troy, as well as drilling undertaken by Austral Gold.
Holeid description name, x, y and z coordinates and total depth, survey, assay and geology tables are in a central database separated by area and can be reviewed in the data base.
Sampling was comprised of Diamond Drilling, Reverse Circulation, and Surface and Underground channels which included:
Manantiales: Drill holes: 67 for an approximate total of 12,652 m. Channels 62 for an approximate total of 540 m. Total Sampling 129 for an approximate total of 13,192 m.
Julieta: DDH Drill holes: 96 for an approximate total of 12,805 m. RC Drill holes: 10 for an approximate total of 1,043 m. Surface Channels: 83 for an approximate total of 376 m. Total Sampling 189 for an approximate total of 14,224 m
Mercado: Drill holes: 100 for an approximate total of 15,232 m. Channels 98 for an approximate total of 1,817 m. Total Sampling 198 for an approximate total of 17,049 m. B-Vein: DDH Drill holes: 311 for an approximate total of 81,609 m. RC Drill holes: 13 for an approximate total of 1,909 m. Underground Channels: 83 for an approximate total of 391 m. Surface Channels: 35 for an approximate total of 803 m. Total Sampling 442 for an approximate total of 84,712 m.
Sampling of core drilling was conducted under geological criteria in which geological and geotechnical logging was performed on the core. The former was carried out by geologists for lithological, structural and mineralogical information, while the latter was done by trained personnel for recovery and RQD information. Core recoveries were consistently high, averaging over 90%.
Reverse Circulation drilling is conducted by drilling a defined drilling interval, generally varying between 0.5 m to 2 m, depending on the objective to be achieved. Once an interval is drilled, the sample is recovered, received in bags that are then mapped and sent for chemical analysis.
Mineralized intervals were selected for assaying for gold and silver content. In cases where the holes were aimed for a specific target, sampling is carried out only in selected intervals of geological interest (veins, veinlets or stockworks), as well as in the adjacent footwall and hanging-wall host rock.
For core drilling, sampling interval length size varies from a minimum of 0.3 m to a maximum of 1.0 m. Diamond Saw half core splitting was conducted on HQ and NQ core holes. Digital photographs were taken of the core to keep a permanent record. Intervals that were not assayed are in storage at the mine site.
Historic drill hole collars were surveyed with industry standard equipment, total station or Differential GPS survey instruments by internal personnel or third-party contractors.
Austral Gold undertook numerous random field checks on historic collar locations. Historic collar locations were generally found to be within ±0.5m of the expected position in data tested.
The database of historical data was validated and compiled by the AGL geology department and reviewed by a corporate Database administrator who have reconciled a representative amount of available hardcopy drill logs and assay results against the digital drill hole database.
Data aggregation methods
In reporting Exploration Results, weighting averaging techniques, maximum and/or minimum grade truncations (eg cutting of high grades) and cut-off grades are usually Material and should be stated.
Where aggregate intercepts incorporate short lengths of high grade results and longer lengths of low grade results, the procedure used for such aggregation should be stated and some typical examples of such aggregations should be shown in detail.
The assumptions used for any reporting of metal equivalent values should be clearly stated.
Significant intercepts are reported directly using its gold and silver grades in ppm. Results are reported to cut-off grade of a 2-ppm gold and allowing for up to 2m of internal dilution between samples above the cut-off grade and 0.2 ppm Au allowing up to 10m of internal dilution between samples above the cut-off grade.
Short lengths of high grade are properly informed indicating its length and grades involved.
The following metals and metal prices have been used to report in this MRE gold grade equivalent (AuEq): Au US$ 2000 / oz Ag US$20/oz most of cases.
Metallurgical recovery assumptions have been applied using mineral processing records from the Casposo plant between 2010 to 2019, particularly used to process Casposo open pit and underground ore.
Several metallurgical testings were performed on each structure of this MRE, and was calculated their own particular recovery for each deposit:
Relationship between mineralisation widths and intercept lengths
These relationships are particularly important in the reporting of Exploration Results.
If the geometry of the mineralisation with respect to the drill hole angle is known, its nature should be reported.
If it is not known and only the down hole lengths are reported, there should be a clear statement to this effect (eg 'down hole length, true width not known').
Four main deposits have been geologically modelled by the team of the Casposo Mine. These structures are Manantiales, Mercado, Julieta and B-Vein and subsequently geostatistic was conducted to determine the metal contents.
The mineralization frame occurs along 10 km long WNW-ESE structural corridor. All the structures are the continuity of the main and previously exploited deposits called Kamila and from south to the north are B-Vein, Mercado, Julieta and Manantiales.
Every single deposit was drilled mostly perpendicular to its main strike and four main deposits have been geologically modelled by the team of the Casposo Mine. These structures are Manantiales, Mercado, Julieta and B-Vein and subsequently geostatistic was performed to determine the metal contents.
The mineralization frame occurs along 10 km long WNW-ESE structural corridor. All the structures are the continuity of the main and previously exploited deposits called Kamila and from south to the north are B-Vein, Mercado, Julieta and Manantiales.
Drilling attempts to cut the mineralized structures at an angle that may adequately represent their width. The modelling considers the intercepts of the orebodies in 3D.
Diagrams
Appropriate maps and sections (with scales) and tabulations of intercepts should be included for any significant discovery being reported These should include, but not be limited to a plan view of drill hole collar locations and appropriate sectional views.
Representative maps and sections are provided in the body of reports released to the ASX.
Balanced reporting
Where comprehensive reporting of all Exploration Results is not practicable, representative reporting of both low and high grades and/or widths should be practiced to avoid misleading reporting of Exploration Results.
Not applicable - reporting Mineral Resources.
Other substantive exploration data
Other exploration data, if meaningful and material, should be reported including (but not limited to): geological observations; geophysical survey results; geochemical survey results; bulk samples - size and method of treatment; metallurgical test results; bulk density, groundwater, geotechnical and rock characteristics; potential deleterious or contaminating substances.
Geological context and observations about the controls on mineralisation where these have been made are provided in the body of the report.
Specific gravity measurements have been taken from the drill core recovered during the drilling program. These data are used to estimate densities in Resource Estimates.
Further work
The nature and scale of planned further work (eg tests for lateral extensions or depth extensions or large-scale step-out drilling).
Diagrams clearly highlighting the areas of possible extensions, including the main geological interpretations and future drilling areas, provided this information is not commercially sensitive.
All available final data have been reported where possible, along with the results of all drilling plans.
Section 3 Estimation and Reporting of Mineral Resources
(Criteria listed in section 1, and where relevant in section 2, also apply to this section.)
Criteria
JORC Code explanation
Commentary
Database integrity
Measures taken to ensure that data has not been corrupted by, for example, transcription or keying errors, between its initial collection and its use for Mineral Resource estimation purposes.
Data validation procedures used.
Initial data collection was completed in MS Excel, visual review and inspections using formulas for errors were completed before import into Vulcan. For drill hole validation to check for issues such as overlapping intervals, missing intervals and intervals beyond hole depth. The validated data was protected and passed to a server workspace to preserve the integrity of the information in charge of the TI department and controlled by the corporate data base administrator.
All lab assay data was imported into the database and paired with sample data by sample ID.
The final database was again validated in Vulcan for overlapping intervals, intervals beyond hole depth, non-consecutive intervals, missing intervals etc. A visual inspection of drill hole locations was completed.
Site visits
Comment on any site visits undertaken by the Competent Person and the outcome of those visits.
If no site visits have been undertaken indicate why this is the case.
A site visit was undertaken by the author of this Technical Report between March 12th to 14th, 2024. I have been on site, and I can review drill holes from each deposit and I can develop a field visit to the location of each deposit, and which ones were subject to studies in this report.
Geological interpretation
Confidence in (or conversely, the uncertainty of ) the geological interpretation of the mineral deposit.
Nature of the data used and of any assumptions made.
The effect, if any, of alternative interpretations on Mineral Resource estimation.
The use of geology in guiding and controlling Mineral Resource estimation.
The factors affecting continuity both of grade and geology.
Reasonable and well developed understanding of geology and morphology of the mineralization was stablished and it was done using geological constrain to identify the geological ore bodies using textures and metal contents, further works were developed to a better understanding of the mineralization based on the hangingwall and footwall geological features that commonly presents brecciation and low grade mineralization in the Casposo Dacite unit also, felsic and andesitic dikes cut the mineralisation which is possible to follow at different levels and sections. Outcrop of the main veins and subordinated structures are well exposed in surface and in oldest open pits and in underground labors. Faulting is well identified and its actions in the main ore bodies are well understood at this time. Some faults may constrain the bounds of the mineralization and offset it vertically and horizontally in places.
Dimensions
The extent and variability of the Mineral Resource expressed as length (along strike or otherwise), plan width, and depth below surface to the upper and lower limits of the Mineral Resource.
Resource block model ranges from surface to approximately 600 m below surface over a strike length ranging of approximately 700 m to 1000 m and from width length from 400 to 550 m. Thickness of the structures are typically between 0.5 and 5 m.
Block Size: Parent: 2.5mx2.5mx2.5m and sub-block 0.5mx0.5mx0.5m
Following tables indicate the Origin, Rotation and offset:
The nature and appropriateness of the estimation technique(s) applied and key assumptions, including treatment of extreme grade values, domaining, interpolation parameters and maximum distance of extrapolation from data points. If a computer assisted estimation method was chosen include a description of computer software and parameters used.
The availability of check estimates, previous estimates and/or mine production records and whether the Mineral Resource estimate takes appropriate account of such data.
The assumptions made regarding recovery of by-products.
Estimation of deleterious elements or other non-grade variables of economic significance (eg sulphur for acid mine drainage characterisation).
In the case of block model interpolation, the block size in relation to the average sample spacing and the search employed.
Any assumptions behind modelling of selective mining units.
Any assumptions about correlation between variables.
Description of how the geological interpretation was used to control the resource estimates.
Discussion of basis for using or not using grade cutting or capping.
The process of validation, the checking process used, the comparison of model data to drill hole data, and use of reconciliation data if available.
A detailed explanation of the estimation and modelling techniques is given in Section 14 of the technical report relating to this resource estimate. It is not practical to describe all aspects of the estimation in JORC Table 1.
Estimation was completed using block modelling and ordinary kriging, these methods are considered appropriate. Top cutting and high-grade restrictions were applied by domains, hard boundary to constrain the main geology feature was applied to prevent smearing the high grades into the low-grade area.
Vulcan software was used to the 3D estimation and geological modelling.
A Block model with the parent cell size 2.5 m x 2.5 m x 2.5 m and sub-cell size 0.5 m x 0.5 m x 0.5 m was generated over the deposit area and restricted to wireframe models. Cell size based on the approximate 25 to 30 m drill spacing of mineralization. Sub blocking was applied to better fit wireframe models.
A variable search geometry was used to follow the strike and dip variations of the deposit where it follows the geometry of the vein structures. A semi-parametric variography model was applied to the deposits.
A univariate estimate was completed.
Geology was used to separate the different geological and stationary domains named as:
MQV: Massive Quartz Vein
BX: Hydrothermal breccia
VLT: Veinlet
Additional Kriging Parameters are as follows defining 5 passes.
Interpolation was conducted at the parent and sub-block scale
Discretization 4x4x4
Negative weights were not set to zero
Maximum of 1 composite and minimum of 2 or 1 composites per drill hole to estimate
Maximum of 6, 4, 2 or 1 composite per search.
Search Radius:
Pass 1: 16 x 0.5 x 16 m
Pass 2: 32 x 0.5 x 32 m
Pass 3: 64 x 1.0 x 64 m
Pass 4: 80 x 1.0 x 80 m
Pass 5: 120 x 2.0 x 120 m.
The model was validated by visual inspection of input and output data as well as statistical validation using boundary analysis and declustered mean comparison.
Moisture
Whether the tonnages are estimated on a dry basis or with natural moisture, and the method of determination of the moisture content.
Bulk density Is based on dry values
Cut-off parameters
The basis of the adopted cut-off grade(s) or quality parameters applied.
Austral will process the material exploited in their own plant facility and all the mineral deposits are in the vicinity of the plant, maximum distance is far 5 km.
At a cut off grade are based on both metals and the definition of income is based on gold equivalent (AuEq) and prices used were USD $2,000 per oz gold and USD $20 per oz silver. Recoveries were applied according to the deposits (see chapter 13).
Open pit cut-off was defined as 1.5 gpt AuEq and Underground cut-off was defined as 2.0 gpt AuEq (further datils see section 14.12).
Mining factors or assumptions
Assumptions made regarding possible mining methods, minimum mining dimensions and internal (or, if applicable, external) mining dilution. It is always necessary as part of the process of determining reasonable prospects for eventual economic extraction to consider potential mining methods, but the assumptions made regarding mining methods and parameters when estimating Mineral Resources may not always be rigorous. Where this is the case, this should be reported with an explanation of the basis of the mining assumptions made.
A Reasonable Prospectus to be exploited was based on open pit and underground optimizations.
Optimizations were developed assuming USD $2,000 per oz gold and USD $20 per oz silver.
Pit shell and Stope optimizer was used to develop the open pit and underground mining respectively.
Further details in section 14.12
Metallurgical factors or assumptions
The basis for assumptions or predictions regarding metallurgical amenability. It is always necessary as part of the process of determining reasonable prospects for eventual economic extraction to consider potential metallurgical methods, but the assumptions regarding metallurgical treatment processes and parameters made when reporting Mineral Resources may not always be rigorous. Where this is the case, this should be reported with an explanation of the basis of the metallurgical assumptions made.
No Metallurgical recovery assumptions have been applied using mineral processing records from the Casposo plant between 2010 to 2019, particularly used to process Casposo open pit and underground ore.
Several metallurgical tests were performed on each structure of this MRE, and was calculated their own particular recovery for each one:
Manantiales Open Pit: Au: 93%, Ag: 80%
Manantiales Underground: Au: 93%, Ag: 75%
Julieta: Au: 87%, Ag: 90%
Mercado: Au: 93%, Ag: 91%
B-Vein: Au: 89.6%, Ag: 87.4%
Environmen- tal factors or assumptions
Assumptions made regarding possible waste and process residue disposal options. It is always necessary as part of the process of determining reasonable prospects for eventual economic extraction to consider the potential environmental impacts of the mining and processing operation. While at this stage the determination of potential environmental impacts, particularly for a greenfields project, may not always be well advanced, the status of early consideration of these potential environmental impacts should be reported. Where these aspects have not been considered this should be reported with an explanation of the environmental assumptions made.
No detailed Environmental Studies, Permitting and Social or Community Impact have been undertaken as part of this study. However, Casposo Mine is a mine complex that worked until 2019, all environmental care was and is carried out even when the operation is in the state of care and maintenance and once operations can restart, all environmental care and compliance required by the legislation of the province of San Juan and the Republic of Argentina demand
Bulk density
Whether assumed or determined. If assumed, the basis for the assumptions. If determined, the method used, whether wet or dry, the frequency of the measurements, the nature, size and representativeness of the samples.
The bulk density for bulk material must have been measured by methods that adequately account for void spaces (vugs, porosity, etc), moisture and differences between rock and alteration zones within the deposit.
Discuss assumptions for bulk density estimates used in the evaluation process of the different materials.
A comprehensive program of systematic bulk density measurement was implemented and developed by AGL and Bulk density, a compilation of 310 samples was provided detailed by rock type and was assigned an average value for each one, were calculated an accumulated and average values and both shows coherent values.
For the MRE was assumed as 2.5 ton/m3 based on the information provided and defined by the mine planning department. Due to the mineralization styles mainly bearing in veins, hydrothermal breccias, stockworks and veinlets, it is fully recommended intensified measurements in the mineralized units.
At this moment the amount of information that was taking in waste units is in a good level, it is recommended to continue with this program intensifying the measurements in mineralized units rather than waste rocks. Only 7 measurements were taken in veins or any type of mineralized rock types and the author agreed in the definition to use a constant value of 2.5 ton/m3 for all rock types.
The basis for the classification of the Mineral Resources into varying confidence categories.
Whether appropriate account has been taken of all relevant factors (ie relative confidence in tonnage/grade estimations, reliability of input data, confidence in continuity of geology and metal values, quality, quantity and distribution of the data).
Whether the result appropriately reflects the Competent Person's view of the deposit.
Classification of Mineral Resources at Casposo uses a criterion based on the risk associated to the distribution of the information as follows:
-Confidence in the Au and Ag estimate.
-Reasonable prospects for eventual economic extraction.
Assessment of confidence in the estimate of grades included guidelines as outlined in JORC (2012).
-Drill data quality and quantity
-Geological interpretation and mineralised domaining.
-The spatial continuity of mineralisation.
The more quantitative criteria relating to these guidelines include data density or grid pattern and the kriging search distances used.
The overall confidence in the geological and mineralised interpretation and domaining is considered high, due in part to the existing mine opening and surface mapping undertaken by Austral Gold staff.
The spatial continuity of mineralisation has shown itself to be consistent in all the geological and stationary domains and the data into those, are geostatistical coherent and valid.
The risk assessment was properly addressed using several sources of information to configurate a drill grid pattern that can assure a risk level according with AGL expectations:
-A benchmarking study was carried out to compare similar Epithermal Low Sulphidation deposits in well-known mines like El Penon, Cerro Bayo and Amancaya in Chile, Cerro Vanguardia, some structures in Cerro Moro and Cerro Negro in Argentina, and Mercedes in Mexico. Most cases are between 20 m to 35 m arrangement and the variability of the gold and silver distributions are key to defining a minor or major drill pattern.
-Key information was the pattern that was used in the past by AGL an previous owner in Casposo Mine. As was stated by the AGL geology team, reliable reconciliations were obtained when was used a 25 m drill hole pattern to declare and define a resource as indicated.
Finally, this information, the benchmarking inputs and the expert criteria of the Competent Person were relevant to define the same drill grid pattern 25 m x 25 m to define indicated resources for Manantiales, Julieta, Mercado and B-Vein deposits.
Formal studies of the optimal grid distance is fully recommended to develop in all of these new deposits in the Casposo Mine, the main goal is to determine the optimal distance between drill holes to ensure the desired level of confidence and error for a year of ore production which is around 400Kton/year according the AGL expectations
Audits or reviews
The results of any audits or reviews of Mineral Resource estimates.
In 2016 RPA develop a comprehensive review of mineral resource estimate covering all the areas of the mine developing a deep analysis of the entire business of the Casposo mine which in the opinion of the author is coherent and appropriate.
Discussion of relative accuracy/ confidence
Where appropriate a statement of the relative accuracy and confidence level in the Mineral Resource estimate using an approach or procedure deemed appropriate by the Competent Person. For example, the application of statistical or geostatistical procedures to quantify the relative accuracy of the resource within stated confidence limits, or, if such an approach is not deemed appropriate, a qualitative discussion of the factors that could affect the relative accuracy and confidence of the estimate.
The statement should specify whether it relates to global or local estimates, and, if local, state the relevant tonnages, which should be relevant to technical and economic evaluation. Documentation should include assumptions made and the procedures used.
These statements of relative accuracy and confidence of the estimate should be compared with production data, where available.
A statistical measure of uncertainty is appropriate at this time.
The highest risk factor ascertaining to the accuracy of the estimate is the interpretation of the mineralized volume and therefore the tonnage of the estimate.
The accuracy of the drill hole collars and digital terrain model over the historic pit area, as well as the data in the historic pit area are key factors the measure this uncertainty.
A qualitative estimate of uncertainty is of the order +/-15 global contained resource tonnes and metal. This is considered by the competent person to be well within the acceptable limits of indicated resource.
Higher-grade assays are also a risk factor, although it should be noted that in relative terms the uncertainty on these high assay values, are mitigated based on the use of thresholds to define the top-cuts and the spatial influence of them avoiding smearing extreme values.
A local estimate has been completed, only tonnages which have a reasonable prospect of economic extraction have been reported as Resources as stipulated by the JORC 2012 code. All Resources are considered relevant to technical and economic evaluation. The use of differential GPS collar surveys mitigates the uncertainty on the location of input data samples and therefore the accuracy of the local estimate.
