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.

Near mine opportunities – open pit targets

In FY2021, Aeris will resume exploration of near mine open pit opportunities at the Golden Plateau target, a large mineralised system with about 800-850,000oz mined to date. The mineralisation remains open down plunge, and modest amount of drilling can improve the deposit knowledge to report an Inferred Mineral Resource.

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

A follow-up RC drill program is being planned later in the current financial year to expand the mineralised system further along strike (north and south) and to test down plunge continuity below higher grade drill intersections.

Aeris will aim to convert all open pit targets to Indicated Mineral Resource status for Feasibility Studies by June 2021.

Recent stratigraphic reinterpretation across the Western Field has provided a greater understanding of the lateral extent, thickness and lithological facies variations within each unit, including the FoD. The underlying volcaniclastic stratigraphic sequence referred to as the ‘FoD’ has historically not been considered prospective.

Drill holes CRD106 and CRD107 were designed to test for lateral continuity of a potentially favourable stratigraphic unit (a coherent intermediate intrusive) located within the FoD at the intersection with the interpreted down dip continuation of the Roses Pride mineralised structure.

Both drill holes intersected the favourable coherent unit within the FoD stratigraphic domain. At the interpreted position of the Roses Pride mineralised structure a subtle fault with weak quartz veining was intersected. Due to the poor volume of epithermal quartz veining, these intersections are not considered prospective and significant assays are not anticipated.  In spite of this, the general target concept remains prospective.

Further drilling will be considered along the newly identified stratigraphic horizon within the FoD further along strike (north). The intent of such drilling would be to test for sites of increased epithermal vein volume, in response to greater dilation along the Roses Pride mineralised structure.

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.

Roses Pride Deeps Exploration Target

Recent stratigraphic reinterpretation across the Western Field has provided a greater understanding of the lateral extent, thickness and lithological facies variations within each unit, including the FoD. The underlying volcaniclastic stratigraphic sequence referred to as the ‘FoD’ has historically not been considered prospective.

Drill holes CRD106 and CRD107 were designed to test for lateral continuity of a potentially favourable stratigraphic unit (a coherent intermediate intrusive) located within the FoD at the intersection with the interpreted down dip continuation of the Roses Pride mineralised structure.

Both drill holes intersected the favourable coherent unit within the FoD stratigraphic domain. At the interpreted position of the Roses Pride mineralised structure a subtle fault with weak quartz veining was intersected. Due to the poor volume of epithermal quartz veining, these intersections are not considered prospective and significant assays are not anticipated.  In spite of this, the general target concept remains prospective.

Further drilling will be considered along the newly identified stratigraphic horizon within the FoD further along strike (north). The intent of such drilling would be to test for sites of increased epithermal vein volume, in response to greater dilation along the Roses Pride mineralised structure.

 

Cross section through the Roses Pride deposit. Showing mined structure and the projected down plunge extension within an interpreted favourable unit below the FoD.

Plan view showing the Roses Pride deposit. Drill collar locations from the 2020 drill program are shown in relation to underground workings and pre-2020 drill collar positions.

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.

Underground Near-Mine Targets

The company has multiple drill-ready underground targets identified on the peripheries of the current Mineral Resource, which will further define the feed for the years to come.

In mine exploration has been successful over many years in extending the known deposits and finding new deposits. Current in-mine exploration targets are;

  • Kenneth target, located close to the Kilkenny and Killarney deposits
  • Killarney depth extension
  • Sterling deposit extensions

Drilling in the second quarter of 2020 will focus on testing the Kenneth exploration target and extensions to existing Mineral Resource inventories. The Kenneth drill target, located along strike from the currently mined Killarney deposit, represents an approximate 350 metre x 100 metre target horizon. There are only two historical drill holes intersecting the target horizon, both of which intersected stockwork quartz veining, including 1m @ 8.3 g/t Au (CBK226). The Kenneth target represents a highly prospective near mine opportunity.

A detailed geological review defining additional drill targets surrounding underground infrastructure was undertaken during the quarter and is expected to be completed in the December quarter. It is anticipated that the review will generate a number of high priority drill targets, sufficient to sustain an additional drill rig throughout the remainder of FY21.

The Sterling target is sparsely drilled in comparison to other underground deposits, and the Baz, Phoenix and Griffin targets are all along strike and down plunge from the current Mineral Resource.

The Ballymore fault structure is also a target for exploration to find new underground deposits. This is described as a greenfield exploration target, although if proved, could be accessed from the existing underground mine.

By June 2022 Aeris will aim to have drill tested all currently identified near mine exploration targets and converted them to Mineral Resource status.

Longer term targets

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

Starting in 2020, 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 North West Corridor has shown outcropping epithermal quartz veining and alteration, as well as anomalous pathfinder elements from rock chip sampling. There is more than 1.5 kilometres of untested strike, within prospective lithology.

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 exploration success.