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.

The Klondyke and Roses Pride targets will also be explored in 2021. Both targets were previously mined underground, with up plunge extensions to mineralisation. The company will spend $2 million to achieve Mineral Resource status at the targets.

ROSES PRIDE DEPOSIT

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).

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.

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

The drillhole data is now being used to generate a maiden Mineral Resource estimate for the shallower section of the Roses Pride mineralised system.

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.

A separate exploration drill program also commenced at the Roses Pride deposit during the quarter, focusing on a conceptual target below previous underground workings.  Previous underground mining at Roses Pride is located within the “upper mineralised panel”, a favourable stratigraphic sequence within the Western Field.  The underlying volcaniclastic stratigraphic sequence referred to as the FoD has historically not been considered to be prospective.  Recent stratigraphic re-interpretation across the Western Field has provided a greater understanding of the lateral extent, thickness and lithological facies variations within each unit, including the FoD.  Importantly, at Roses Pride the FoD unit is interpreted to thin, from ~ 450 metres further north to less than 100 metres thick beneath Roses Pride.

The conceptual target is a repeat of the Roses Pride mineralised system at depth within an inferred favourable stratigraphic horizon beneath the FoD.  An initial two hole drill program will be completed, targeting the conceptual stratigraphic / structural target horizon. There is scope to increase the drill program dependent on results.

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

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 Deposit

The Roses Pride high grade deposit represents the northernmost 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.

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 Roses Pride forms along one prominent fault traced over 1km along strike, with several minor mineralised splays in the footwall and hanging wall.

A surface RC drill program completed in June 2020 was designed to test the up plunge and along strike (north) continuity of the mineralised system beyond the current mine footprint.  An updated geological interpretation and Mineral Resource estimate was completed after the 2020 drill program.

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.

Cross section through the Roses Pride deposit showing the main mineralised structure and two hanging wall splay faults.

MINERAL RESOURCE STATEMENT OVERVIEW

Geology and Geological Interpretation

Gold mineralisation at Roses Pride is hosted in steeply dipping low sulphidation epithermal veins.  These veins are found as discrete lodes (often with stockwork veining), composed of quartz, carbonate and adularia, with varying percentages of each mineral.  Epithermal vein textures include banding (colloform, crustiform, cockade, moss), breccia channels and massive quartz; all indicative of depth within the epithermal system.  Gold is very fine grained and found predominately as electrum but less commonly within clots of pyrite.

Estimation domains are based on a combination of lithological and gold grade information.  Both discrete vein lode domains and halo or stockwork domains were interpreted separately.  The dominant mineralised structure and mineralised splay faults are characterised by robust quartz/carbonate vein development with logged vein percentages >50%.  Peripheral stockwork domains are characterised by erratic and generally low grade gold mineralisation.  A 0.1g/t Au cut-off grade was used to define the margins of the stockwork domains.

Drilling and sampling techniques

Sample data used for estimation include a combination of underground face samples (73%), diamond drill hole samples (20% including half core HQ and NQ and full core LTK60) and RC samples (7%).  Face sample data is located within the existing mined Mineral Resource. The remaining Mineral Resource is informed by diamond drilling and RC samples.

Sample intervals for drill core and face samples were determined by visual logging of lithology type, veining style/intensity and alteration style/intensity to ensure a representative sample was taken. Sampling lengths ranged from a minimum of 0.4m to a maximum of 1.2m with sampling completed across the full width of mineralisation. RC samples were collected on 1m intervals.

Surface and underground drill core was halved with a core saw, with one half dispatched for analysis and the other half retained. All underground LTK60 was whole core sampled, with a small number of underground NQ holes whole core sampled during 2013. RC samples were collected with a cyclone and 7-1 split was taken at the drill rig using a riffle splitter.

Whole/half core samples were crushed in a jaw crusher to > 70% passing 2mm; half of this material was split with a riffle splitter for pulverising. No RC samples required crushing in the jaw crusher. Core and RC samples were pulverised for 10-14 minutes in a LM5 bowl with a target of 85% passing 75µm. From this material approximately 120g was scooped for further analysis and the remaining material re-bagged.

Sample preparation for rock chip face samples was conducted at the Cracow onsite laboratory. Samples were crushed in a Jaw Crusher to 100% passing 5mm; this material was then split with a riffle splitter and pulverised for 4 minutes in a LM2 bowl with a target of 85% passing 75µm. From this material 400g was collected with a scoop and sent for transport to ALS laboratory for assaying.

Estimation parameters

Ordinary kriging using 1m composite data was used to estimated gold and silver into a block model with a parent block size of 5.0m (east) x 10.0m (north) x 10.0m (RL).  A total of 17 estimation domains have been used ranging from high grade gold epithermal structures, mineralised fault splay to low grade gold stockwork zones.  Hard boundaries were used between all estimation domains.  A variety of different search parameters were used as deemed appropriate for the specifics of each domain.  Gold and silver composites were capped prior to estimation.  The resource model was validated via visual and statistical methods.

Mineral Resource Classification

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 Measured, Indicated and Inferred Mineral Resource.  Measured Mineral Resource is constrained to drill spacing less than 20m x 20m and includes level development through the mineralised vein.  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.

Cut-off grade

The Mineral Resource is reported within nominal 2.2g/t Au shells from the main Roses Pride epithermal structure and splays off the structure.  In places a small amount of material below cut-off is included in some reporting shells to maintain a consistent and coherent profile.  It is expected mining of the Mineral Resource would be via underground mining methods.  There is an opportunity to extract near surface Mineral Resource via open pit.  The near surface mineralisation extractable via open pit mining is considered to represent a modest proportion of the total reported Mineral Resource.

Klondyke – Royal Near Surface Drill Target

An RC drill program was completed across the Klondyke and Royal deposits during the first quarter 2020.  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.

In total, 23 shallow RC drill holes were completed within the Klondyke to Royal corridor.  The assay results are encouraging with several significant drill hole intersections, including:

  • 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).

Klondyke and Royal longsection view showing Au intersections from the recently completed 2020 drill program (annotated) and pre 2020 drilled Au intersections.

Plan view showing the Klondyke and 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.