Cracow

Aeris acquired the Cracow Gold Operation from Evolution Mining in June 2020. Cracow has a long history of resource and reserve replenishment and has consistently extended the life of mine, with a three to five-year mine life maintained since 2011.

The Cracow Gold Operations are located in a highly endowed goldfield with gold mineralisation hosted in steeply dipping structurally controlled low sulphidation epithermal veins.

Total Mineral Resource at 30 June 2020 was 2.3 million tonnes at 4.0 grams per tonne gold (300,000 ounces of contained gold) with Ore Reserve of 0.55 million tonnes at 5.1 grams per tonne gold (89,000 ounces of contained gold).

All mining is currently by underground narrow vein methods. Historically, there have been open pit mines at several locations on the property with future production likely to come from a combination of underground mining and open pit operations.

The open pit projects being taken forward to prefeasibility study are:

  • Roses Pride pit (extension of an old pit);
  • Klondyke pit; and
  • Golden Plateau pit (extension of an old pit).

Underground mine production is from several of the known deposits in the field all connected by underground drives to the one portal at surface. Ore is produced using narrow vein bench stoping, occasional cut and fill stopes, and up-hole retreat benching. Dry rock fill is used as the most common backfill. Where required, a cemented rock fill will be placed to allow for pillar recovery. The stoping method is described as Avoca or Modified Avoca depending on the access constraints.

Aeris has allocated $13 million for targeted drilling and near mine exploration, as well as a re-evaluation of material that is not currently in a resource category.

Aeris has a detailed exploration plan for near mine brownfields targets over a two-year period, and will be exploring greenfield targets in its highly prospective tenement package.

Key exploration activities undertaken during the quarter included:

  • Underground resource definition drilling;
  • Test down plunge extension along the Klondyke structure; and
  • Commencement of an RC resource definition drill program at the Roses Pride deposit.

Underground resource definition drilling

Resource definition drilling in the June quarter focused on testing extensions to the known mineralised systems at the Crown, Tipperary, Royal and Sterling deposits.

Drilling at the Crown deposit successfully intersected the mineralised structure down plunge beneath the current mined portion of the deposit.  The preliminary drill program intersected the mineralised structure over a 200m strike length and up to 80m down plunge below current workings.  Intersections occur within and below the reported Mineral Resource footprint.  Significant intersections include:

  • CRU159 – 5.5m @ 15.92g/t Au (3.8m true thickness)
  • CRU161 – 7.15m @ 5.26g/t Au (4.4m true thickness)
  • CRU160 – 1.1m @ 12.86g/t Au (0.8m true thickness)

Long section view showing location of diamond drill holes completed or assays received within the quarter at the Crown deposit.

Klondyke – Down Plunge Extensions

The Klondyke mineralised structure hosts the Royal and Cracow deposits, which combined have contributed approximately 800,000oz of gold via underground mining between 2004 to 2009.  These orebodies were hosted by competent (rheologically brittle) andesite lava sequences of the Permian Camboon Volcanics.  A thick, rheologically ductile volcaniclastic unit occurs below this favourable horizon and was believed to terminate economic ore shoot development on the fertile structures.

Recent radical advances in stratigraphic definition at Cracow have highlighted the presence of a competent basaltic andesite unit below the thick volcaniclastic unit, indicating the potential for re-development of economic mineralisation down plunge from known orebodies.

Limited drilling within the underlying volcaniclastic unit have intersected veining along the Klondyke structure.  Vein and geochemical vectors from those drill intersections indicate the fluids are still within the precious metal window conducive to low sulphidation epithermal mineralisation.

During the quarter an exploration drill hole (CRU171) was drilled from underground, targeting the Klondyke structure approximately 300m down plunge from previous drilling.  The drill hole interested the Klondyke structure at the interpreted position with stockwork quartz veining developed along the structure.  Based on quartz vein textures, wall rock alteration and geochemistry, the intersection is interpreted to be marginally below the low sulphidation epithermal window.  The drill hole does indicate it is possible further mineralisation could develop beneath the known ore shoots.  Along the Klondyke structure further drill targets have been identified and will be tested in FY22.

Roses Pride Near Surface Drill Target

The Roses Pride high grade deposit represents the northernmost ore deposit mined at Cracow since modern mining commenced in 2004.  Underground activities at Roses Pride accessed and mined the deposit to 200 metres below surface.  Intermittent surface drill programs have been completed in the past, seeking to define up-plunge, near surface extensions to the Roses Pride mineralised system.  Prior drilling had been successful in intersecting the mineralised structure above and along strike from underground workings, however the results had not been sufficient to enable a Mineral Resource estimate to be generated.

Aeris announced on 31 August 2020, the results from the recent near-surface Reverse Circulation (RC) drilling program on the Roses Pride deposit.  The intent of the 2020 RC drill program was to systematically drill test the interpreted mineralisation above and along strike (north) of the underground workings.  The drill program was completed on a nominal 20 metres (strike) x 20 metres (down dip) spacing along a 400 metre strike length.

Assay results have returned for 4 drillholes from the 2020 RC drill program and are highly encouraging, with gold mineralisation intersected along the entire drilled strike length (400 metres). Significant drillhole intersections from the program include:

  • RPS003 19.0m @ 5.45 g/t Au (true thickness 10.1 m);
  • RPS025 15.0m @ 4.10 g/t Au (true thickness 6.1m);
  • RPS050 5.0m @ 5.33 g/t Au (true thickness 3.3m);
  • RPS054 10.0m @ 5.13 g/t Au (true thickness 4.7m).

Roses Pride long section view showing Au intersections from the recently completed 2020 drill program (majority annotated) and pre 2020 drilled Au intersections

During the quarter a follow-up surface RC drill program commenced at the Roses Pride deposit.  The resource definition drill program is designed to complete infill drilling surrounding the previous drill campaign conducted last year, which led to the increase in the reported Mineral Resource at Roses Pride.  The drill program will also test for extensions to the mineralised system further down plunge below the current drilling footprint.

Long section view showing location of RC drill holes completed during the quarter at the Roses Pride deposit.

Roses Pride December 2020 Reported Mineral Resource

As announced on 6 January 2021, Mineral Resource Update, the increased Inventory is based on a combination of additional drilling data and an alternate reporting schema.

The updated Mineral Resource was reported from within nominal 2.2g/t Au cut-off shells.  In some places blocks below cut-off were included within the reported volume to retain a geometry consistent with a potential “mineable” shape.  The previous Mineral Resource was reported at a 2.8g/t Au cut-off within a more tightly constrained footprint around the current mine workings.

Table 1: December 2020 Roses Pride Mineral Resource[1],[2].

December 2020 Roses Pride Mineral Resource

Resource Category Tonnage (kt) Au (g/t) Ag (g/t) Au metal (koz) Ag metal (koz)
Measured
Indicated 104.1 4.7 2.1 15.6 7.0
Inferred 73.0 4.5 2.2 10.5 5.1
TOTAL 177.1 4.6 2.2 26.1 12.1

[1] Discrepancy in summation may occur due to rounding.
[2] Mineral Resource is reported within a nominal 2.2g/t Au cut-off shell.

Table 2: December 2019 Roses Pride Mineral Resource1,[1].

December 2019 Roses Pride Mineral Resource
Resource Category Tonnage (kt) Au (g/t) Ag (g/t) Au metal (koz) Ag metal (koz)
Measured 0.2 17.3 0.1
Indicated 4.2 13.1 1.8
Inferred 21.6 7.7 5.4
TOTAL 26.1 8.7 7.3

[1] Mineral Resource is reported within above a 2.8g/t Au cut-off peripheral to current mine workings.

Resource classification was based primarily on drill density with some consideration given to the confidence of the model, geological complexities including vein geometry and continuity, faulting, assay variability.

The resource model has been classified as Indicated and Inferred Mineral Resource.  Indicated Mineral Resource is reported from areas with a drill density up to 40m x 40m.  Inferred Mineral Resource is classified either from drill spacings up to 60m x 60m or projected a maximum of 15 metres beyond the base of Indicated Mineral Resource.

Long section view showing the December 2020 reported Roses Pride Mineral Resource block estimate.  Blocks are coloured by Au grade.  Outline of previously reported Mineral Resource denoted by solid blue line.

KLONDYKE – ROYAL DEPOSIT

The Klondyke and Royal deposits are two high grade gold lodes located along the Klondyke fault.  The deposits are located along the south eastern margin of the current underground mining activities within the Western Field at Cracow.

Gold mineralisation is hosted in steeply dipping low sulphidation epithermal veins along fault structures.  Vein textures include colloform, crustiform, cockage, breccia channels and massive quartz.  Mineralisation at both deposits form along one prominent fault traced over 1km along strike, with several minor mineralised splays in the footwall and hanging wall.  Both deposits extend approximately 400m along strike.

An surface RC drill program was completed in June 2020 and was designed to test the up-plunge extents to the known mineralised systems above the mining footprint and outside the reported Mineral Resource (refer to September 2020 Quarterly Activities Report).  In total, 23 shallow RC drill holes were completed within the Klondyke to Royal corridor.  Significant assay results from the drill program include:

  • KDS002 7.0m @ 11.6 g/t Au (true thickness 3.3 m);
  • KDS003 3.0m @ 3.2 g/t Au (true thickness 1.7m);
  • KDS017 4.0m @ 2.9 g/t Au (true thickness 1.4m);
  • KDS015 6.0m @ 2.5 g/t Au (true thickness 2.8m).

This additional drilling accounted for 5,042 ounces of the 27,261 total gold ounce increase in the updated Mineral Resource.

Klondyke and Royal longsection view showing Au intersections from the June 2020 drill program

The Klondyke and Royal deposits are high grade shoots which form along the same mineralised structure.  The drill program was designed to infill around existing drill hole data above the higher grade Klondyke deposit and test the extents to mineralisation along the structure between both deposits.

Klondyke – Royal  March 2021 Reported Mineral Resource

The updated Klondyke – Royal Mineral Resource (Table 1) is reported in accordance with the Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves 2012 (JORC Code).  Material changes from the previously reported Klondyke – Royal Mineral Resource (Table 2) include the conversion of additional mineralisation to JORC classified Indicated and Inferred categories via a revised geological model/reporting framework and additional drilling data.

Table 1: March 2021 Klondyke – Royal Mineral Resource[1],[2].

March 2021 Klondyke – Royal Mineral Resource
Resource Category Tonnage (kt) Au (g/t) Ag (g/t) Au metal (koz) Ag metal (koz)
Measured
Indicated 183.4 4.0 3.6 23.5 21.2
Inferred 158.0 3.1 2.1 15.9 10.4
 
TOTAL 341.3 3.6 2.9 39.5 31.6

Table 2: June 2020 Klondyke – Royal Mineral Resource[1],[3].

June 2020 Klondyke – Royal Mineral Resource
Resource Category Tonnage (kt) Au (g/t) Ag (g/t) Au metal (koz) Ag metal (koz)
Measured
Indicated 16.8 6.6 4.0 3.5 2.2
Inferred 45.7 5.9 9.9 8.7 14.5
 
TOTAL 62.6 6.1 8.3 12.2 16.7

The updated Mineral Resource was reported from within the main mineralised structure where the mineralised vein thickness exceeds 1.5 metres at a 1.5g/t Au cut-off.  The previous Mineral Resource was reported at 2.2g/t Au (Royal) and 2.8g/t Au (Klondyke) cut-off grades, within more tightly constrained conceptual mine designs around the historical mine workings.

[1] Discrepancy in summation may occur due to rounding.

[2] Mineral Resource is reported within a combined 1.5g/t Au cut-off and vein thickness ≥ 1.5m envelope.

[3] Mineral Resource is reported within a 2.2 g/t Au (Royal) and 2.8g/t Au (Klondyke) cut-off peripheral to current mine workings. Reported Mineral Resource was constrained within conceptual mine designs at a AUD$2,300 metal price.

Plan view showing the Klondyke – Royal deposits. Drill collar locations from the 2020 drill program are shown in relation to underground workings and pre-2020 drill collar positions.

Longer term targets

In the longer term, greenfield exploration opportunities will be developed through Aeris’ highly prospective tenement package, which remains largely underexplored.

In FY22 Aeris will commence drilling at the Ballymore target to test the structure further along strike. The Ballymore target is a newly identified structure along the southern margin of the current mining footprint. Limited drilling at the site has returned encouraging evidence of epithermal vein textures, and anomalous pathfinder elements including gold.

The Cracow South West exploration target represents a potential analogue of the Western Field low sulphidation epithermal system which is has been the focus of underground mining activities since 2004.  The Cracow South West target has had limited exploration previously, principally because it is under several hundred metres of cover sequences.  Previous exploration including 2D seismic lines and a limited drill program were successful in identifying several fault structures with low level gold anomalism.  Aeris plan to complete a magneto-telluric survey over the area followed by a first pass drill program.

At the Boughyard target, a large (~3.0kmx1.5km) alteration system is open to the south and west. In the longer term, Aeris will evaluate the exploration potential of the highly prospective tenement package that includes the New England Fold Belt, where there is excellent potential for near mine and regional