HomeMediaProject UpdatesBROKEN HILLDiamond core tests demonstrates high-grade cobalt-zinc potential at Broken Hill

Diamond core tests demonstrates high-grade cobalt-zinc potential at Broken Hill

  • CCZ’s geology team re-tested diamond core – from drill-holes BH1 & BH2 at the “The Sisters” Prospect (1) (East Zone, BHA Project) – available at the core library in Broken Hill, NSW, with encouraging results:
    • Utilising a PXRF analyser – to identify samples for follow upassays – readings up to 1,705ppm Co and 9.63% Zn were recorded
    • More significantly, several wide PXRF intervals (7-9m wide) were delineated with high-grade cobalt-zinc readings (Figure 1)
    • These identified intervals from the BH1 & BH2 core (Appendix B) are being sent to the laboratory for follow up analysis

The above results are an average of two readings taken for 60 seconds and are preliminary. They are being used to identify sections for core re-sampling and subsequent laboratory analyses. They are not being used in the block model and do not replace laboratory analyses.

FIGURE 1: PRXF INTERVALS BH1 & BH2 – THE SISTERS PROSPECT

  • The PXRF analysis for BH1 & BH2 is consistent with earlier assayed sections from the same diamond core (over different depths), with the best results comprising: 1.8m @ 820ppm Co from 124.7m (BH1) and 1.5m @ 320ppm Co from 138.4m (BH2)(2) – Refer Appendix C
  • There is a primary 1,200m synclinal structure at The Sisters Prospect (3) – which BH1 intersected – that appears to host high-grade cobalt-zinc mineralisation: this is now a key target for further drill-testing
  • In addition, further forensic work on codifying the 6,380 drill-holes around the Reefs Tank & Tors Tank Prospects found more evidence of shallow cobalt mineralisation, with the best intercepts: 7m @ 1,600ppm Co from 30m (drillhole 1800E1180N); 15m @760ppm Co from 67m (3E51N); 10m @ 520ppm Co from surface (2925E1240S); and 5m @520ppm Co from 45m (TT05W10N)(4)
  • The Board is optimistic there is adequate geological data across The Sisters, Reefs Tank & Tors Tank Prospects to potentially prove up a primary cobalt JORC 2012 compliant mineral resource estimate

Castillo Copper’s CEO Dr Dennis Jensen commented: “The preliminary results from analysing The Sisters Prospect’s diamond core has delivered Castillo Copper an excellent outcome. We now have compelling evidence, subject to final assays, there is high-grade cobalt-zinc mineralisation apparent and a prime target for future test drilling. Furthermore, the Board believes that, once all the assays are in from The Sisters Prospect, there will be sufficient data to potentially prove up a primary global cobalt mineral resource estimate that complies with the JORC 2012 Code.” 

Castillo Copper Limited (“CCZ”) Board is delighted to report a successful trip by the geology team to the core library in Broken Hill, NSW, where they analysed diamond core from drill-holes BH1 and BH2 at The Sisters Prospect (1) within the East Zone, BHA Project.

HIGH GRADE COBALT-ZINC POTENTIAL

The objective of the trip to the core library in Broken Hill was to find incremental evidence (from analysing untested diamond core from BH1 & BH2) to demonstrate the presence of cobalt-zinc mineralisation at The Sisters Prospect (1) (Figure 2).

Using a PXRF analyser, purely to identify parts of the diamond core for follow up assays, the initial readings returned up to 1,705ppm Co and 9.63% Zn. Further, there were several wide PXRF intervals that delineated high-grade cobalt-zinc mineralisation, including (refer Figure 1 & Appendix B):

  • 9.05m @ 859ppm Co & o.26% Zn from 11.84m
  • 8.42m @897ppm Co & 3.26% Zn from 116.24m
  • 7.26m @ 946ppm Co & 1.53% Zn from 106.62m
  • 4.88m @ 370ppm Co & 0.89% Zn from 124.66m (Appendix B)

Due to these findings, the identified intervals from BH1 & BH2 diamond core are being sent to the laboratory for a complete analysis to confirm the results reconcile with the PXRF observations.

The results are an average of two readings taken for 60 seconds and are preliminary. They are being used to identify sections for core re-sampling and subsequent laboratory analyses. They are not being used in the block model and do not replace laboratory analyses.

FIGURE 2: THE SISTERS PROSPECT, EAST ZONE, BHA PROJECT

FIGURE 2: THE SISTERS PROSPECT, EAST ZONE, BHA PROJECT

Previous assays of the diamond core from BH1 & BH2, from different sections to where the PXRF analysis targeted, returned encouraging results, with the best intercepts comprising: 1.8m @ 820ppm Co from 124.7m (BH1) and 1.5m @ 320ppm Co from 138.4m (BH2)(2) – refer Appendix C for further details. As such, when reconciling the historical assays with the recent PXRF results, it provides a relatively high degree of confidence there is significant potential to extend the known cobalt mineralisation once verified by assays.

Indeed, according to a previous report3 there is a primary 1,200m synclinal structure at The Sisters Prospect – which BH1 intersected – that appears to host high-grade cobalt-zinc mineralisation. As can be seen in Figure 3, most historic drilling campaigns missed this structure completely. Consequently, it is now a key target for further drill-testing once a timeline is set to undertake an inaugural drilling campaign at The Sisters Prospect. 

FIGURE 3: THE SISTERS HISTORICAL DRILL-HOLES – COBALT PPM BY LABORATORY ASSAY

Reefs Tank & Tors Tank Prospects

Ongoing work to codify the 6,380 drill-holes around the Reefs Tank & Tors Tank Prospects – within the defined target area – has found more evidence of shallow cobalt mineralisation, with the best intercepts: 7m @ 1,600ppm Co from 30m (1800E1180N); 15m @ 760ppm Co from 67m (3E51N); 10m @ 520ppm Co from surface (2925E1240S); and 5m @ 520ppm Co from 45m (TT05W10N)(4).

Primary cobalt MRE

Assessing the preliminary findings holistically across The Sisters, Reefs Tank & Tors Tank Prospects, the Board is optimistic there is adequate geological data to potentially prove up a primary cobalt JORC 2012 compliant mineral resource estimate.

Next steps

In NSW:

  • JORC 2012 compliant mineral resource estimate for the BHA Project East Zone.

In Queensland:

  • Assay results for Arya Prospect.
  • Big One Deposit – formalising timing for next drilling campaign.

In Zambia:

  • Complete geophysical report on the Mkushi Project; and
  • Complete work on the inaugural drilling campaign for the Luanshya Project.
References
  1. CCZ ASX Release – 9 March 2022 AND Glifillan J.F., 1971, Report on Exploration by Falconbridge (Australia) Pty Ltd on ATP 3091 Broken Hill Area NSW under option from Minerals Recovery (Australia) N.L., Falconbridge (Australia) Pty Limited, Jan 1971, 93pp
  2. CCZ ASX Release – 15 March 2022 and 9 March 2022
  3. Gilfillan J.F., 1971, Report on Exploration by Falconbridge (Australia) Pty Ltd on ATP 3091 Broken Hill Area NSW under option from Minerals Recovery (Australia) N.L., Falconbridge (Australia) Pty Limited, Jan 1971, 93pp
  4. Leyh, W.R., and Lees T., 1977, Progress Report on Exploration Licence, No. 846 Iron Blow -Yellowstone Area, Broken Hill, New South Wales for the six months period ended 29th June 1977, North Broken Hill Limited, Report GS1976-198, Jul 77, 35pp AND Leyh, W.R., 1990, Exploration Report for the Third Six Monthly Period ended 12th June 1990 for EL 3238 (K Tank), Broken Hill District, New South Wales for the six months period, Pasminco Limited, Report GS1989-226, Jun 90, 22pp AND Main, J.V., and Tucker D.F., 1981, Exploration Report for Six Month Period 8th November 1980 to 7th May 1981, EL 1106 Rockwell, Broken Hill, NSW, CRA Exploration Pty Ltd, GS1980-080, Jul 1981, 40pp