Helix’s 100%-owned Collerina Copper Project is located in the highly active copper/gold mining and exploration district known as the Cobar Basin, within central NSW, Australia.

The Collerina Copper Project comprises a tenement package in excess of 1,500km2, including over 85km of copper-prospective trend. It is surrounded by multiple operating base metal and gold mines within the broader Cobar Basin (Tritton, Hera, Peak and CSA mines).

The Central Zone deposit is a Helix internally generated, high-grade copper discovery within the Collerina Copper Project. High-grade results from previous drilling of the Central Zone deposit include: 11m at 6.6% Cu, 12m at 5.0% Cu, 14m at 4.0% Cu and 10m at 3.7% Cu.

In June 2019, Helix announced a maiden resource estimate for the Central Zone deposit of 2.02 Mt at 2.03% Cu and 0.1g/t Au for 40kt copper and 9.4koz gold (Indicated and Inferred) (refer Table C). Almost 50% of that resource tonnage sits in the Indicated categorisation, with the remainder classified as Inferred.

In early 2020 an RC drilling program tested for further high-grade copper mineralisation in the Exploraton Target zone immediately surrounding the initial Central Zone resource(refer Table C).

The drilling program successfully identified new zones of high-grade copper well outside the current Central Zone resource envelope (see Figure 1).  These results represent significant extensional success and clear validation of the broader Collerina Deposit Exploration Target. Importantly they provide an opportunity to substantially grow the high-grade copper resource at Collerina.

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Figure 1: Schematic long section of the Central Zone Resource envelope showing selected intercepts along the plunge extent of the resource (refer Table 1).

Preliminary Engineering and Geological Target Studies

The primary objective of the 2020 conceptual work at the Collerina Copper Project was to provide a clearer understanding of how any future Central Zone pit shape may be influenced and constrained by the current resource model, and where additional drilling could be undertaken to target a Resource increase for inclusion in any future mining scenarios.

Helix engaged consultant engineers to model conceptual pits using the initial Collerina Central Zone JORC Resource block model and various copper prices between US$3.00/lb to US$4.00/lb. This conceptual work was not undertaken as any indicator of economic viability or production targets, but expressly to highlight areas where the current drilling density was constraining the resource This information in turn will be used to guide the next round of drilling.

Specifically, the work was successful in identifying gaps in the drilling in the vicinity of mineralised holes from historical drilling undertaken by CRA to the immediate north west. It is noted that these historic holes were intentionally omitted from the current resource estimate as they did not conform to JORC 2012 requirements

The modelling provided increased confidence in the current geological model with mineralisation continuity expected to be enhanced with the identified further drilling and with the aim of increasing the current JORC resource.

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Figure 2: Schematic 3D image (looking south-west) with copper drill intercepts, Central Zone Resource Envelope (yellow), Exploration Target Implicit Model (red-transparent), Conceptual Pit outline (blue-transparent) and plunges of the northern and southern targets zones.

Scale Potential

Down dip from Central Zone

  • Massive, semi-massive and disseminated copper sulphide mineralisation was intersected in a targeted zone approximately 180m down-dip from the delineated Central Zone resource envelope.
  • The key intercept of 4m @ 3.18% Cu and 0.4g/t Au from 218m (including 1m @ 6.44% Cu and 0.8g/t Au from 218m)2 (primary material) was returned in CORC116 (see Figure 4 and 5).

Along strike from Central Zone

  • Holes drilled into this extensional target intersected zones of oxide and transitional copper mineralisation in two broad fence lines of drilling. The best result of 11m @ 1.04% Cu (oxide/transitional) from 58m (including 3m @ 2.79% Cu (transitional) from 66m)2 was returned in CORC107.
  • Significantly, these results are interpreted to represent the up-plunge position of the Northern Target Zone. This implies a full structural repeat of the Central Zone style plunge from surface as the Northern Target Zone extends to untested FLEM targets approximately 1.5km down plunge (which is approx. 550m from surface).
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Figure 2: Schematic long section of the Northern Target Zone showing selected intercepts and new EM positions along the plunge extent of the zone down to the FLEM target at depth(Refer Table C).

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Figure 3: Cross section showing down dip Northern Target Zone located over 180m down dip from current Central Zone Resource envelope

Footwall to Central Zone

  • A broad zone of oxide copper mineralisation had previously been observed in a hole drilled approximately 40m west-southwest of CORC009 (53m at 0.5% Cu from surface, including 5m at 4.2% Cu from 48m to end-of-hole)2.
  • Targeting a footwall fold nose target, and drilled in the current program, CORC111 returned 46m @ 0.44% Cu from 3m including 1m @ 4.9% Cu from 31m2 (massive copper oxide – malachite). This provides strong confirmation of additional footwall mineralisation behind/below the Central Zone resource (Southern Target Zone).
  • Broad zones of shallow oxides were also present in CORC112 (12m @ 0.11% Cu from 20m) and CORC120 (30m @ 0.18% Cu from 33m). CORC121 intersected semi-massive chalcopyrite in a fault zone (1m @ 2.88% Cu from 58m)2.
  • Significantly, the host geology is similar to the Central Zone however appears to be overturned, consistent with a repeat fold closure.

Downhole Electromagnetic (DHEM) analysis has proven to be a highly effective tool for targeting thicker, higher grade copper sulphide mineralisation within the Central Zone Resource envelope at Collerina. DHEM surveys were undertaken on select holes from the recent RC program.  A number of strong on-hole and off-hole responses have been identified and plates modelled. The positions of the new plates boost confidence in the plunge targets on both the new Northern Target Zone and the new Southern Target Zone (see Figure 6).

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Figure 6: Plan view of the Collerina Deposit, showing the current resource (Orange) within the new sulphide ribbon (Blue) interpretation. DHEM modelled plates complement recent drilling results confirming strike, dip and plunge extensions well outside the current Central Zone resource envelope.

Central Zone Mineral Resource Estimate (June 2019) (0.5% Cu Cut-off)
Classification Type











Indicated Oxide / Transitional 0.17 1.1 0.0 1,900 200
Inferred Oxide / Transitional 0.46 0.6 0.0 2,700 100
Total Oxide / Transitional 0.63 0.7 0.00 4,600 300
Indicated Fresh 0.83 2.6 0.2 21,800 6,600
Inferred Fresh 0.57 2.5 0.1 14,100 2,500
Total Fresh 1.40 2.6 0.2 35,800 9,100
Indicated Oxide / Transitional 0.17 1.1 0.0 1,900 200
Indicated Fresh 0.83 2.6 0.2 21,800 6,600
Inferred Oxide / Transitional 0.46 0.6 0.0 2,700 100
Inferred Fresh 0.57 2.5 0.1 14,100 2,500
Total Combined 2.02 2.0 0.1 40,400 9,400

Other than results contained in this ASX release, Helix confirms that it is not aware of any new information or data that materially affects the Mineral Resource information included in Helix ASX release dated 11 June 2019, Interim Maiden Resource at Collerina Copper Project. All material assumptions and technical parameters underpinning the estimates in that release continue to apply and have not materially changed.

The Central Zone resource lies within a larger Exploration Target envelope (which has been constrained between interpreted cross-cutting faults, coincident with the strike of the surface geochemical footprint and shallow copper oxide drilling). The Exploration Target consists of an additional 2 – 5Mt at similar grades of approximately 1.5 – 3.0% Cu (representing a potential additional 30 – 150kt contained copper).

While the near-surface strike continuity of the Collerina mineralisation is now well understood, the potential quantity and grade of the Exploration Target remains conceptual until drill tested. Geophysical and structural evidence provides confidence in the geometry and dimensions, however, there has been insufficient drilling within these new plunge extensions to estimate Mineral Resources in the broader shape. It should be considered uncertain as to whether further exploration drilling will result in the definition of additional Mineral Resources within or beyond the Exploration Target envelope.

Project Details
Collerina Copper Project
Helix Resources Limited 100%
Cobar Basin NSW
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