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Valeriano Project

The 3,795-ha Valeriano Project is located approximately 125 km to the southeast of the City of Vallenar, Atacama Region, Chile and 27 km northeast of Barrick’s Veladero Mine. Road-accessible Valeriano is adjacent to the El Encierro Antofagasta (51%) - Barrick (49%) joint venture. The project is within an emerging copper-gold porphyry belt - the Link Belt - between the Maricunga and El Indio belts. Elevations vary from 3,800 to 4,400 metres above sea level.

The Valeriano Project hosts a large copper gold porphyry deposit, overlain by a near surface oxidized epithermal gold deposit that extends from surface to a depth of 100 metres.

In 2020, ATEX reported initial mineral resources for both the oxide gold deposit and copper gold porphyry. In 2022, ATEX completed the company's first test of the porphyry system. The two holes completed established a very large porphyry system and outlined a +1% CuEq core at Valeriano.

Phase III drilling, starting in October, will use directional drilling to extend the high-grade trend, test new targets and expand the mineralized envelope.

Based on an option agreement from August 2019, and amended in January 2020, ATEX can earn a 100% interest in Valeriano by September 1, 2025. For details of the payments and work commitments, please see the company's corporate presentation.

ATEX optioned the Valeriano property in 2019 and completed initial resource estimates for the copper-gold porphyry and epithermal gold oxide deposits in late 2020.

In early 2021, ATEX completed a 1,708 metre Reverse Circulation “RC” program with the goal of exploring the growth potential of the epithermal gold oxide deposit.

The 2022 exploration program was designed to follow up on and expand the copper-gold porphyry-style mineralization initially encountered by the previous operator in 2013. This program was designed to further define and extend high-grade copper-gold mineralization intersected in hole VALDD-14, which returned 1,194 metres of 0.73% CuEq, including 1.00% CuEq over 272 metres. ATEX drill holes following up on this hole were drilled as 200 metre step outs to the northeast and southwest to test the high-grade extension.

Hole ATXD-17, the most impressive hole drilled to date at Valeriano, with results reported on June 13, 2022, was drilled 200 metres southwest of VALDD14 and demonstrated the continuity of the high-grade target zone, intersecting 1,160 metres of 0.78% CuEq, including 1.03% CuEq over 550 metres. Hole ATXD-19, collared 200 metres northeast of VALDD-14, was lost at a depth of 1,309 metres due to operational issues and did not reach the high-grade target zone. Despite not reaching its target depth, ATXD-19 intersected 647 metres of 0.65% CuEq, establishing continuity of copper gold mineralization a further 200 metres to the northeast. Of note, the top 650-metre intervals with +0.4% CuEq reported in VALDD-14 (0.63% CuEq) and, in ATXD-17 (0.64% CuEq) are comparable to the grades in ATXD-19 and prove the consistency of the porphyry mineralization.

Significant Porphyry intersections are summarized below in Table 1.

HoleID From
Hole Length
ATXD-17 802 1,962 1,160 0.53 0.28 70 0.78 2,057
including 1,280 1,830 550 0.69 0.39 70 1.03  
ATXD-193 662 1,309 647 0.50 0.15 60 0.65 1,309
VALDD-09 898 1,750 852 0.47 0.16 89 0.64 1,878
VALDD-14 614 1,808 1,194 0.52 0.24 36 0.73 1,845
including 1,420 1,692 272 0.72 0.28 21 1.00  
VALDD-16 576 1,621 1,045 0.39 0.17 54 0.54 1,621

Table 1. Summary of Significant Copper-Gold Porphyry Assay Results1

  1. The copper-equivalent grade was calculated using a copper price of $2.60/lb, gold price of $1,450/oz and molybdenum price of $11.00/lb (all prices in US$).  Metal recoveries were not considered.  The formula for calculating the copper-equivalent is: CuEq% = ((Cu%/100 * Cu $/tonne) + (Au g/t * Au $/gr.) + (Mo%/100 * Mo $/tonne)) / Cu $/tonne.
  2. Unless otherwise indicated, intervals are composited at a 0.40% CuEq cut-off and a 10 m width internal dilution. All intervals are reported as core lengths as the true lengths of the intervals are unknown at this time.
  3. ATXD-19 includes a 24 m interval grading 0.35% CuEq from 762 to 786 m.

Exploration pre-ATEX.

Exploration at Valeriano commenced in the 1980’s. Initial regional exploration, consisting of outcrop and float sampling, returned anomalous results followed by the acquisition of the concessions by the vendor. Further sampling and trenching was carried out through the 1980’s and into the 1990’s, targeting the near surface alteration features. Through the 1990’s, various drill campaigns were completed by three operators, Phelps Dodge (1989-1991), Barrick (1995-1997) and Hochschild (2011-2013). The initial focus of exploration was on the near-surface oxide gold potential, transitioning to a focus on the porphyry potential by 2013. To date, 32,365 metres in in 78 holes (20,982 metres of diamond drill core and 11,383 metres of RC drilling) have been completed on the property. Work by historical operators is summarized below in Table 2.

Company Period Surface samples Trenching (m) Geophysics IP (Km) Geophysics Mag (Km) Mapping Special Studies*
J. Ambrus 1986              107        
Rayrock 1988              403         720.0    
Phelps Dodge 1989-1991                 27         961.0      
Newmont 1993-1994           450.0                 32.0
Barrick 1995-1997              693         664.0            15.3               51.7
Hochschild 2010-2014                36.0  
Totals             1,230      2,795.0            51.3               83.7    

Table 2. Historical exploration activities
*Special studies include Petrography, Fluid inclusions, SWIR and age-dating

During the 1990’s, Phelps Dodge and later Barrick explored the Valeriano property for near-surface gold mineralization, drilling 47 holes to an average and maximum depth of 267 metres and 550 metres, respectively. The drill programs outlined a zone of near-surface, high sulphidation, epithermal gold mineralization over an area of approximately 400 metres by 400 metres to depths of approximately 100 metres below surface. Drill intercepts included 89 metres of 1.50 g/t Au (drill hole RDH-V27) and 0.62 g/t Au over 170 metres (RDH-V31). 

In 2010, Hochschild optioned the Valeriano property and completed 16 diamond drill holes in three campaigns for a total of 14,270 metres. During the second drill campaign, Hochschild recognized porphyry-style alteration at depth and in the third season they drilled three holes, collared approximately 225 metres to 375 metres apart, to depths of up to 1,878 metres, intersecting well-defined mineralized advanced argillic and phyllic alteration zones before entering a chalcopyrite and bornite-bearing, potassic-altered granodioritic porphyry system.  

A summary for drilling completed till the end of the H1 2022 field season is shown below in Table 3. 

Company  Target  Period  RC  DDH  Holes  Total 
      # metres # metres # meters
Phelps Dodge  Au-Ox/Cu  1989-1991  18  3,500.0  2,902.7  27  6,402.7 
Barrick  Au-Ox  1995-1997  20  6,175.0        20  6,175.0 
Hochschild  Cu-Au Porphyry  2011-2013        16  14,269.7  16  14,269.7 
ATEX  Au-Ox  2021-2022  12  1,708.0             
   Cu-Au Porphyry           3,809.7  15  5,517.7 
Totals     1989-2021  50  11,383.0  28  20,982.1  78  32,365.1 

Table 3. Summary of drilling at Valeriano 1989-2022 

The Valeriano Project is located along a north-south trending metallogenic belt extending through northern Chile and into Argentina. This belt, internally referred to the as the “Link Belt”, connects the Maricunga gold porphyry belt to the north with the El Indio epithermal gold belt to the south. The Link Belt hosts a number of significant copper-gold porphyry deposits, including Filo del Sol (Filo Mining), Josemaria (Lundin Mining), Los Helados (NGEX Minerals/Nippon Caserones Resources), La Fortuna (Teck Resources/Newmont), and El Encierro (Antofagasta/Barrick Gold). 

Regionally, a large surface alteration zone or lithocap, of approximately 13 kilometres by 4.5 kilometres, extends from the Valeriano property northward to Antofagasta/Barrick Gold’s resource-stage El Encierro Project. The epithermal gold oxide deposit at Valeriano is hosted within the lithocap, which overlays the copper-gold porphyry. 

The geological setting for the Valeriano property is characterized as a sequence of Permo-Triassic felsic volcanics, intruded by various granodioritic mineralized porphyries. The emplacement of these porphyries generated a large hydrothermal system, exhibiting a classic example of zoned alteration from the porphyry through to the epithermal setting. The lithocap above the porphyry exhibits high-level advanced argillic alteration with local epithermal gold silver mineralization, which transitions into a well-developed potassic alteration zone within the porphyry environment. Breccias and quartz filled stockworks are generated adjacent to and within the porphyries and host disseminated copper-gold mineralization.   

Mineralization at Valeriano occurs in a zoned sequence, initially as a high-sulphidation epithermal expression near-surface where, primarily gold, mineralization occurs within the advanced argillic alteration zone above the porphyry. This zone transitions with depth into a more copper-rich environment between the epithermal and porphyry system where covellite replaces pyrite. Porphyry-related mineralization then occurs within the porphyry stock and intrusive breccias with copper-gold mineralization occurring mainly as disseminated chalcopyrite and lesser bornite. 

Resource Statement as at November 13 2020:

Resource Table

1 Notes to accompany Cu-Au Porphyry Resource table:

  1. Mineral resources are not confined by economic or mining parameters.
  2. Cut-off grades are for reporting purposes only and no economic conditions are implied.
  3. CuEq grades are calculated based upon a Cu price of $3.00 per pound, Au price of $1,800 per oz and Ag price of $25.00 per oz (all prices in US$). Minor discrepancies may exist due to rounding. Metal recoveries were not considered.
  4. Formula for CuEq% calculation: CuEq (%)=(Cu_ppm)/10,000+((Au(g/t)*(Au)price)/( 22.0462*31.0135*(Cu price ))+ ((Ag(g/t)*(Ag)price)/( 22.0462*31.0135*(Cu)price))
  5. Tonnage and grade estimates are in metric units. Contained gold ounces are reported as troy ounces.

2 Notes to accompany Epithermal Au Resource table:

  1. Mineral resources are not confined by economic or mining parameters.
  2. Cut-off grades are for reporting purposes only and no economic conditions are implied.
  3. Au equivalent grades are calculated based upon a Au price of $1,800 per oz and a Ag price of $25.00 per oz (all prices in US$). Minor discrepancies may exist due to rounding. Metal recoveries were not considered.
  4. Formula for AuEq calculation: AuEq (g/t)=Au(g/t)+((Ag(g/t)*(Ag)price)/(Au)price))
  5. Tonnage and grade estimates are in metric units. Contained gold ounces are reported as troy ounces.
  6. Estimated copper grades, at the 0.275 g/t cut-off grade, are 0.06%.

Resource Estimation Methodology

The Gold Oxide Resource Estimate is based upon 4,455 metres in 55 drill holes (1,148 metres in 19 diamond drill holes and 3,307 metres in 36 reverse circulation drill holes) from the 1990’s Barrick Gold Corp. (“Barrick”) and Phelps Dodge Corporation (“Phelps Dodge”) exploration programs and from Hochschild Mining plc’s (“Hochschild”) 2011 to 2013 drilling programs. A total of 2,209 composites were used in the estimation, virtually all 2 metres length. The resource estimation units are based on ATEX’s three-dimensional models for lithology and mineralization that were built using geological units from Hochschild’s core logging and taking into account structure controls and correlogram reach. The Gold Oxide Resource Estimate lies within the oxide 3-D shell and is confined to three volcanic and volcaniclastic units (sandstone, agglomerate and rhyolite). The majority of the Oxide Resource extends to depths of approximately 100 metres below surface, locally extending deeper. Within the rhyolite sequence, the Oxide Resource is restricted to upper 85 metres of the rhyolite unit as statistical analyses shows that the gold grade drops significantly below that horizon.

After geostatistical analysis of the gold grades within the 3-D estimation units, and prior to the resource estimation, mineralized versus non-mineralized material was defined by indicator kriging for each unit. Variography was analyzed by means of correlogram maps, down the hole correlograms and directional correlograms. Final results indicated an overall horizontal isotropy and vertical anisotropy. The resource was estimated via Ordinary Kriging in 4 passes. Samples assaying greater than 4.00 g/t Au in agglomerate, 1.65 g/t Au in upper rhyolite and 0.29 g/t Au in sandstone were capped. The resulting 10 x 10 x 10-metre block model was validated by means of global and conditional bias assessments as well as by drift analyses. The Copper Gold Porphyry Resource Estimate is based upon 2,701 metres of diamond drilling in four drill holes completed by Hochschild.  A total of 1,353 composites were used in the estimation, almost all with a length of 2 metres. 

The Copper Gold Porphyry Resource Estimate is based upon 2,701 metres of diamond drilling in four drill holes completed by Hochschild. A total of 1,353 composites were used in the estimation, almost all with a length of 2 metres. The Porphyry Resource is limited to the zone of dominant chalcopyrite copper mineralization. The three-dimensional chalcopyrite model was built using Hochschild core logging information taking into account structure controls. The chalcopyrite 3D shell was separated in two units: 1) higher grade being hosted within the granodiorite porphyry and the south breccia (“Cpy_gd_bx”); and 2) moderate grade within all other intrusives, breccias and rhyolite host rock (“Cpy_other”). After geostatistical analysis of copper grades within the 3-D estimation units, and prior to the resource estimation/calculation, mineralized versus non-mineralized material was defined by indicator kriging for each unit. Variography was analyzed by means of correlogram maps, down the hole correlograms and directional correlograms.  Final results indicated an overall horizontal isotropy and vertical anisotropy.  The resource was estimated via Ordinary Kriging in 4 passes. Samples assaying greater than 1.2% Cu in Cpy_gd_bx and 1.0% Cu in Cpy_other were capped. Gold grades were capped in the chalcopyrite shell by host-rock: 0.80 g/t Au (granodiorite), 0.53 g/t Au (rhyolite, diorite porphyry & breccia) and 0.47 g/t Au (south breccia & PQDH). The resulting 10 x 10 x 10metre block model was validated by means of global and conditional bias assessments as well as by drift analyses.

No specific gravity measurements have been completed on mineralized material from either the oxide gold resource or the copper gold porphyry resource. An estimated specific gravity of 2.5 has been used for both resource estimates. Samples for specific gravity analyses are currently be collected from drill core from the 2012 – 2014 drilling program.

Given the current drill density for the Porphyry Resource, partial lack of data for complete QA/QC analyses in the Oxide Resource and absence of specific gravity data, both resource estimates have been classified as inferred.

Qualified Persons

SRK Consulting (Chile) SpA. undertook to prepare and is responsible for the resource estimate.  Joled Nur, Civil Mining Engineer, SRK Consulting (Chile) SpA and a member of the Public Register of Competent Persons in Mining Resources and Reserves of Chile, No. 181, is the independent qualified person (“QP”), as defined by National Instrument 43-101 Standards for Disclosure for Mineral Projects, who prepared the resource estimates.  Mr. Nur has reviewed and approved the disclosure related to the resource estimates within this press release. David Hopper, the independent QP for the Valeriano Project, is a Chartered Geologist of the Geological Society of London, Fellow No. 1030584.  Mr. Hopper has reviewed and approved the technical disclosure within this press release. 5 The Valeriano resource estimates have been prepared under Canadian Institute of Mining, Metallurgy and Petroleum Definition Standards (2014).  

Quality Assurance / Quality Control

The diamond drilling core from Hochschild’s 2011 to 2013 drilling campaign were collected and sampled under the direct supervision of Hochschild’s staff.  Diamond drill core was placed in core boxes at the drill site, appropriately tagged, secured and transported to the Hochschild’s exploration camp.  Drill core was logged, marked, on average, at 2 metre intervals for sampling and split longitudinally with a diamond drill saw.  One half of the core was bagged and sample tags attached and the second half of the core was returned to the core boxes. All samples were appropriately labelled and transported by truck by Hochschild personnel to the ALS Chemex laboratory located in Coquimbo, Chile.  ALS Chemex-Coquimbo carried out preparation, chemical analyses and QA/QC. The preparation protocol (PREP-31B) consisted of crushing 70% to less than 2 mm (-10#), rotary split of 1 kg and pulverization to better than 85% passing 75 microns (-150#). Gold was analyzed via 50-gram fire assay and AA. Thirty-five additional elements, which included Cu, Ag, molybdenum and arsenic were assayed using aqua regia digestion and ICP-AES analysis (protocol ME-ICP41).

Hochschild´s QA/QC protocol for drill hole samples included field, coarse reject and pulp duplicates of samples, blanks, and Au and Cu standards. At least 20% of the samples were sent for assay comprised quality assurance duplicates, blanks and standards.

ATEX reviewed QA/QC data obtained during Hochschild’s 2011-2013 drilling campaigns. A total of 7,397 drillhole samples were collected in holes VALDD-01 through VALDD-16.  Details are as follow:

  • Field, coarse reject and pulp duplicates totalled 890 Au assays of which 342 were assayed for Cu.
  • A total of 345 standards were inserted; 323 Au standards and 22 Cu standards.
  • A total of 628 coarse (-10#) and fine (-150#) blanks were assayed.

Overall conclusions drawn from the QA-QC analyses are as follows:

  • Analyses of duplicates show good precision indicating that the protocols used for sample preparation and assaying were adequate.
  • Analyses of standards used during exploration show good accuracy, however, one Au standard showed a consistent negative basis (-15.77%).
  • Analyses of blanks showed no serious contamination problems between samples.  

The overall conclusion is that the available QA-QC data generated by Hochschild for the Valeriano drill program meets acceptability criteria for the stage of the project and the exploration data can be used for modeling and estimation of inferred resources.

There is no QA/QC data available from the Phelps Dodge drilling program.  From drill logs, it is apparent that diamond core was sampled based upon geological controls in areas of potential mineralization and was sampled and assayed at 1-metre intervals in areas of no apparent mineralization.  Drill core recovery appears to have been good.  The sampling protocol resulted in variable sample lengths in areas of interest typically from 10 to 50 centimeters.  In the case of reserve circulation drill holes, sampling was completed at 1-metre intervals and the entire drill hole was sampled and assayed. There is no information available regarding the sample preparation or assaying methods used by Phelps Dodge.

There is no QA/QC data available and little sample or assaying methodology information available from the Barrick reverse circulation drilling program other than sampling was undertaken at 1-metre intervals and sampling commenced at the beginning of the drill holes. 

Considering the seniority of the companies and the professionals involved at the time, there is no apparent reason to question the validity of the Phelps Dodge or Barrick assaying information.  The assay results are internally consistent within the oxide resource area, geologically reasonable for the type of deposit and intensity of mineralization and are comparable to the assay results returned by Hochschild drilling in the same area. It is therefore considered reasonable that these results be included in the estimation of an inferred resource on an early stage exploration property.

Details of historical exploration, including drilling, sampling and assaying, together with ATEX’s QA-QC analysis and commentary are available in the “NI 43-101 TECHNICAL REPORT ON THE VALERIANO PROJECT, ATACAMA REGION, CHILE” dated November 25, 2020 and filed at www.sedar.com.

Sensitivity Tables to Resource Estimates

Valeriano Copper-Gold Porphyry Resource Estimate – Inferred Category

Cut-off Cu
Grade Contained Metal
Cu Eq.
Cu Eq.
0.2 684.58 0.49 0.163 0.91 0.64 3,321,772 3,590,244 20,039,444 4,374,922
0.3 645.33 0.50 0.167 0.91 0.66 3,225,909 3,473,140 18,882,439 4,242,805
0.4 515.43 0.53 0.180 0.97 0.70 2,746,126 2,986,710 16,030,960 3,619,818
0.5 297.30 0.59 0.193 0.90 0.77 1,766,743 1,844,884 8,621,904 2,301,579
0.6 142.93 0.65 0.198 0.81 0.83 926,661 908,024 3,730,162 1,187,958
0.7 15.74 0.73 0.235 0.91 0.95 115,180 118,723 458,731 149,235

Valeriano Gold Oxide Epithermal Resource Estimate – Inferred Category

Cut-off Au
Tonnes Grade Contained Ounces
Au Eq.
Au Ag Au Eq.
0.200 62,819,175 0.395 2.16 0.425 797,662 4,361,385 858,244
0.225 51,842,530 0.434 2.22 0.464 722,647 3,691,909 773,917
0.250 41,119,097 0.485 2.32 0.517 641,089 3,065,582 683,664
0.275 34,435,360 0.528 2.40 0.561 584,684 2,653,895 621,539
0.300 28,900,615 0.574 2.44 0.608 533,581 2,269,764 565,106
0.350 20,891,789 0.670 2.56 0.706 450,033 1,719,813 473,922
0.400 15,750,241 0.767 2.61 0.804 388,574 1,321,227 406,924

In early 2022, ATEX completed a deep penetrating magnetotelluric (“MT”) geophysical survey and a ground magnetic survey (“Mag”) over the entire Valeriano property. Both surveys were successful in establishing a clear association with previous surveys completed by third parties.

Modelling of the MT survey data down to 2,000 metres depth identified a zone of low resistivity, coincident with a subcircular chargeability and low-resistivity anomaly, three kilometres in diameter, outlined by a historical induced polarization (“IP”) survey that penetrated to a depth of 800 metres. The mineralization within the Valeriano Copper-Gold Deposit correlates well with the broad MT resistivity anomaly that extends significantly to depth and laterally, suggesting continuation of the porphyry mineralization in all directions.

High-grade corridors have been interpreted over the Magnetization Vector Inversion (MVI) image from the recent Mag survey. A western high-grade corridor concurs with the +1.0% CuEq zones of drill holes ATXD-17 and VALDD-14. An untested eastern corridor is suggested by the magnetic survey, below the collar of drill hole VALDD-16, not cut by this hole. The corridors have a N-S to NNE strike coincident with general attitude of outcropping intermineral porphyries and mineralization at El Encierro.

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