Havieron Mineral Resource Estimate Update
Source: RNS
Greatland Gold plc (AIM: GGP)
E: info@greatlandgold.com
W: https://greatlandgold.com
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NEWS RELEASE | 21 December 2023
Havieron Mineral Resource Estimate Update
Exceptional Mineral Resource growth continues at Havieron
THIS ANNOUNCEMENT CONTAINS INSIDE INFORMATION AS STIPULATED UNDER THE UK MARKET ABUSE REGULATIONS. ON PUBLICATION OF THIS ANNOUNCEMENT VIA A REGULATORY INFORMATION SERVICE, THIS INFORMATION IS CONSIDERED TO BE IN THE PUBLIC DOMAIN.
Greatland Gold plc (AIM:GGP) ("Greatland" or the "Company") is pleased to provide an updated Mineral Resource Estimate for Havieron, its flagship gold-copper project located in the Paterson Province of Western Australia.
Highlights
§ Estimated Mineral Resources (including Ore Reserves) increased to 8.4Moz AuEq1 (7.0Moz Au plus 275kt Cu), an increase of 1.9M oz AuEq1 from Greatland's 2022 Mineral Resource Estimate:
- 29% increase in total gold equivalent content to 8.4M oz AuEq1.
- 28% increase in total gold content to 7.0M oz Au.
§ Continuous mineralisation confirmed between the Eastern Breccia and main Havieron Breccia domains with the definition of a new high grade "Link Zone".
§ Drilling since Greatland's previous Mineral Resource Estimate (MRE) update in March 2022 targeted the lower portion of the mineral system and has increased the ounce per vertical metre (OPVM) profile of these lower levels in line with the upper levels of the deposit. The updated MRE now averages 7,900 OPVM (gold equivalent) over the top 1,000 metres vertically.
§ The MRE update includes a 32% increase in contained gold equivalent metal in the higher confidence Indicated MRE category, which can now be considered in the updated Ore Reserve Estimate that will be part of the Feasibility Study.
The updated MRE incorporates approximately 93,000 metres additional drilling completed since the December 2021 drilling cut-off for Greatland's March 2022 MRE.
Updated Mineral Resource Statement for the Havieron Deposit (100%) # *
|
Classification |
Tonnage |
Grade |
Metal |
AuEq Metal |
||
|
Mt |
Au (g/t) |
Cu (%) |
Au (Moz) |
Cu (Kt) |
AuEq (Moz) |
|
|
Indicated |
50 |
2.6 |
0.33 |
4.1 |
168 |
5.0 |
|
Inferred |
81 |
1.1 |
0.13 |
2.9 |
107 |
3.4 |
|
Total Mineral Resource |
131 |
1.7 |
0.21 |
7.0 |
275 |
8.4 |
# Grades are reported to one (gold) and two (copper) decimal places to reflect appropriate precision in the estimate, and this may cause apparent discrepancies in totals. Results represent 100% of the Mineral Resource for Havieron. Mineral Resources in the South East Crescent and Link Zone are reported within a A$80 Net Smelter Return2/t ("NSR2/t") shell while Mineral Resources in the Breccias are reported within a A$50 NSR2/t shell. Resources are inclusive of Reserves.
* The updated Mineral Resource Estimate assumes selective mining of the South East Crescent and Link Zone and bulk extraction in the Breccias and are reported inside A$80 or A$50 NSR2/t shells respectively.
Greatland Managing Director, Shaun Day, commented:
"We are delighted by the continued growth in the Havieron Mineral Resource Estimate. The growth journey in the resource has been very significant with the total gold equivalent Mineral Resource content having increased from 4.4M oz in the October 2021 MRE, to 6.5M oz in the March 2022 MRE, and now to 8.4M oz in 2023.
The updated MRE now averages over 7,900 ounces per vertical metre (gold equivalent) over 1,000 metres vertically, which is testament to the quality of the Havieron ore body.
The high grade South East Crescent Zone Mineral Resource is now defined over a 1,200 vertical metres (another 200 metres deeper than in the March 2022 MRE update) and remains open at depth.
It was particularly pleasing to delineate additional ounces in the lower third of the current extents of the mineralised system, with around 70% of the MRE increase identified in the extensions to this part of the ore body.
Another promising aspect of this update is the definition of the Link Zone, between the Eastern Breccia and main Havieron Breccia; whilst previously interpreted as separate domains, we have now confirmed mineralisation is continuous and the breccias are now defined as a singular continuous Breccia domain.
This update further demonstrates the quality and scale of Havieron, and the compelling investment proposition for Greatland. We are excited to see the impact of the significant growth in the Indicated category on the updated Ore Reserve Estimate that will underpin the Feasibility Study which is ongoing and expected to be completed in 2024."
Important notes
Mineral Resource estimates are expressions of judgement based on knowledge, experience and industry practice. They are also based on a number of material assumptions (such as future commodity prices and foreign exchange, cut off grades) which may prove to be incorrect. Estimates which were valid when originally made may alter significantly when new information or techniques becomes available. In addition, by their very nature, Mineral Resource estimates are imprecise and depend to some extent on interpretations, which may prove to be inaccurate. Unless and until actually mined and processed, no assurance can be given that any estimated tonnage, grades and recovery levels will be realised.
This announcement and the updated Mineral Resource Estimate for the Havieron Project contained in it have been prepared solely by Greatland based on relevant available information and have not been reviewed or approved by Greatland's Havieron joint venture partner, Newmont Corporation (Newmont). Newcrest Operations Limited, a subsidiary of Newmont, is the manager of the Havieron Joint Venture and holds the majority 70% joint venture interest. Whilst the information in this announcement pertaining to the estimation and reporting of the Mineral Resources has been reviewed and approved by a Competent Person3 and the updated Mineral Resource estimate has been independently reviewed by SRK Consulting (Australasia) Pty Ltd4, the Company considers that it is possible that, in preparing any future Mineral Resource estimate or Ore Reserve estimate for the Havieron project, Newmont may adopt different interpretations, assumptions, parameters or plans, or make different judgements, to those used or made by Greatland in the updated Mineral Resource Estimate contained in this announcement.
Forward Looking Statements
This document includes forward looking statements and forward looking information within the meaning of securities laws of applicable jurisdictions. Forward looking statements can generally be identified by the use of words such as "may", "will", "expect", "intend", "plan", "estimate", "anticipate", "believe", "continue", "objectives", "targets", "outlook" and "guidance", or other similar words and may include, without limitation, statements regarding estimated reserves and resources, certain plans, strategies, aspirations and objectives of management, anticipated production, study or construction dates, expected costs, cash flow or production outputs and anticipated productive lives of projects and mines.
These forward looking statements involve known and unknown risks, uncertainties and other factors that may cause actual results, performance and achievements or industry results to differ materially from any future results, performance or achievements, or industry results, expressed or implied by these forward-looking statements. Relevant factors may include, but are not limited to, changes in commodity prices, foreign exchange fluctuations and general economic conditions, increased costs and demand for production inputs, the speculative nature of exploration and project development, including the risks of obtaining necessary licences and permits and diminishing quantities or grades of reserves, political and social risks, changes to the regulatory framework within which Greatland operates or may in the future operate, environmental conditions including extreme weather conditions, recruitment and retention of personnel, industrial relations issues and litigation.
Forward looking statements are based on assumptions as to the financial, market, regulatory and other relevant environments that will exist and affect Greatland's business and operations in the future. Greatland does not give any assurance that the assumptions will prove to be correct. There may be other factors that could cause actual results or events not to be as anticipated, and many events are beyond the reasonable control of Greatland. Forward looking statements in this document speak only at the date of issue. Greatland does not undertake any obligation to update or revise any of the forward looking statements or to advise of any change in assumptions on which any such statement is based.
Footnotes:
1 The gold equivalent (AuEq) is based on assumed prices of US$1,700/oz Au and US$3.75/lb Cu for Mineral Resource and metallurgical recoveries based on block metal grade, reporting approximately at 87% for Au and 87% for Cu which in both cases equates to a formula of approximately AuEq = Au (g/t) + 1.6* Cu (%). It is the company's opinion that all the elements included in the metal equivalents calculation have a reasonable potential to be recovered and sold.
2 The Net Smelter Return ("NSR") is calculated using metal prices of US$1,700/oz Au and US$3.75/lb Cu, metallurgical recoveries based on block metal grade reporting approximately at 87% for Au and 87% for Cu, an USD:AUD exchange rate of 0.72, as well as treatment and refining costs, payables and royalties.
3 See Competent Person's Statement below for details.
4 See Section titled "Independent Review of the Mineral Resource Update".
Contact
For further information, please contact:
Greatland Gold plc
Shaun Day, Managing Director | info@greatlandgold.com
Nominated Advisor
SPARK Advisory Partners
Andrew Emmott / James Keeshan / Neil Baldwin | +44 203 368 3550
Corporate Brokers
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Media Relations
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About Greatland
Greatland is a mining development and exploration company focused primarily on precious and base metals.
The Company's flagship asset is the world-class Havieron gold-copper project in the Paterson Province of Western Australia, discovered by Greatland and presently under development in joint venture with world gold major, Newmont Corporation.
Havieron is located approximately 45km east of Newmont's existing Telfer mine. The box cut and decline to the Havieron orebody commenced in February 2021. Total development now exceeds 3,060m including over 2,110m of advance in the main access decline (as at 22 November 2023). Subject to a positive feasibility study and Decision to Mine, Havieron is intended to leverage the existing Telfer infrastructure and processing plant. Access to Telfer will de-risk the development and reduce capital expenditure.
Greatland has a proven track record of discovery and exploration success and is pursuing the next generation of tier-one mineral deposits by applying advanced exploration techniques in under-explored regions. Greatland has a number of exploration projects across Western Australia and in parallel to the development of Havieron is focused on becoming a multi-commodity miner of significant scale.
Further Information on the Updated Mineral Resource at Havieron
Havieron Project
The project comprising the Havieron Au-Cu deposit is centred on a deep magnetic anomaly 45km east of Telfer (Figure 1) in the Paterson Province of Western Australia on the traditional lands of the Martu people. The Project is held in a joint venture between Greatland and Newcrest Operations Limited, a wholly owned subsidiary of Newmont Corporation (Newmont), where Newmont currently holds a 70% joint venture interest (Greatland 30%).
The Martu people and the Jamukurnu-Yapalikurnu Aboriginal Corporation (JYAC, formerly WDLAC) are key project stakeholders. The Martu hold exclusive possession native title rights and interests over more than 140,000km2 of land, including to all points around the Telfer mine and Havieron Project. The Indigenous Land Use Agreement (ILUA) with JYAC, centred on the Telfer mine, extends to the Havieron project.
The Havieron project is located within granted Mining Lease M45/1287 and has received the necessary regulatory approvals for the construction of a box cut, exploration decline and certain associated surface infrastructure. Construction commenced in January 2021, and total development now exceeds 3,060m including over 2,110m of advance in the main access decline (as at 22 November 2023), with the decline now at a depth of approximately 340 vertical metres with 80 vertical metres remaining to the base of the Permian layer.
A pre-feasibility study for Havieron was completed in October 2021, and a feasibility study is ongoing with several value enhancing options being assessed to maximise value and de-risk the project.
Figure 1. Location of the Havieron Project, approximately 45km east of Telfer, Western Australia.
Drilling Overview
Drilling at Havieron commenced during mid-2019 with a total of 368 drill holes for 295,657m considered suitable to inform the MRE. This total excludes non-exploration drilling (e.g. geotechnical, hydrological, etc), and drilling considered not suitable (e.g. holes which failed to reach target).
An additional 92,648m of drilling has been incorporated into this updated MRE relative to the March 2022 MRE. This additional drilling comprised a combination of growth and resource conversion drilling, both of which have been extremely successful in increasing the MRE.
The growth drilling has resulted in a 29% increase in contained gold equivalent metal in this updated MRE, with additional ounces defined within the Northern Breccia, Eastern Breccia and South East Crescent. A new high grade zone has also been defined, the "Link Zone" which confirms continuous mineralisation between the Northern Breccia, South East Crescent and the Eastern Breccia.
The Resource conversion drilling targeted the upgrade of previously defined Inferred South East Crescent MRE into the higher confidence Indicated category, and has increased South East Crescent Indicated MRE material from 26Mt to 36Mt, a greater than 30% increase to the previous March 2022 MRE. The importance of this conversion is that the Indicated MRE category can underpin Ore Reserve Estimates, whereas the Inferred MRE category cannot due to its lower confidence.
Updated Mineral Resource Estimate
The updated MRE for the Havieron Deposit prepared by Greatland (Table 1) ("Updated Mineral Resource") is based on drilling completed to 6 June 2023, comprising 368 holes for 295,657m, inclusive of 107 holes for 92,648m which are additional to the drilling data incorporated in Greatland's March 2022 MRE released on 3 March 2022.
Table 1: Updated Mineral Resource Estimate tabulation for the Havieron deposit (100%) # *
|
Domain |
Classification |
Tonnage |
Grade |
Metal |
AuEq Metal |
||
|
Mt |
Au (g/t) |
Cu (%) |
Au (Moz) |
Cu (Kt) |
AuEq (Moz) |
||
|
South East Crescent |
Indicated |
36 |
3.0 |
0.42 |
3.5 |
150 |
4.2 |
|
Inferred |
8 |
2.1 |
0.19 |
0.6 |
15 |
0.6 |
|
|
Link Zone |
Indicated |
2 |
2.7 |
0.20 |
0.1 |
3 |
0.2 |
|
Inferred |
5 |
1.4 |
0.26 |
0.2 |
12 |
0.3 |
|
|
Breccia |
Indicated |
13 |
1.3 |
0.11 |
0.5 |
14 |
0.6 |
|
Inferred |
68 |
0.9 |
0.12 |
2.1 |
79 |
2.5 |
|
|
Total Mineral Resource |
131 |
1.7 |
0.21 |
7.0 |
275 |
8.4 |
|
# Grades are reported to one (gold) and two (copper) decimal places to reflect appropriate precision in the estimate, and this may cause apparent discrepancies in totals. Results represent 100% of the Mineral Resource for Havieron. Mineral Resources in the South East Crescent are reported within a A$80 Net Smelter Return2/tonne ("NSR/t") shell while Mineral Resources in the Breccias are reported within a A$50 NSR/t shell. Resources are inclusive of Reserves.
* The Updated Mineral Resource Estimate assumes selective mining of the South East Crescent Zone and bulk extraction in the Breccias and are reported inside A$80 or A$50 NSR2/t shells respectively.
The updated MRE is reported as Indicated and Inferred Mineral Resources in accordance with the 2012 edition of the Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves (the JORC Code). The reported updated Mineral Resources are inclusive of Ore Reserves. Refer to details in Appendix 1 (JORC Table 1 - Sections 1 to 3) for information relating to data collection and resource estimation.
The updated MRE represents a significant increase on the MRE previously announced by Greatland in March 2022, including a:
§ 43% increase in total (Indicated plus Inferred) tonnes;
§ 28% increase in total gold ounces; and
§ 29% increase in total gold equivalent ounces.
Material differences between the Updated Mineral Resource and the previously announced March 2022 Mineral Resource are as follows:
§ A further 92,648 metres of infill drilling completed in the approximately 18 months since December 2021 to 6 June 2023 when surface drilling ceased.
§ Drilling has confirmed continuous mineralisation exists between the Northern Breccia, South East Crescent and the Eastern Breccia, in essence confirming that the Eastern Breccia forms part of the same continuous breccia body that hosts the main Havieron deposit. This has resulted in an increase in the breccia Resources and the definition of a new high grade domain.
§ Drilling has provided adequate geological confidence to define a new domain, the Link Zone, which is a moderately dipping approximately 30m wide by 200m long zone of mineralisation that extends northwards from the existing South East Crescent Zone at the 4,000mRL down to the 3750mRL. This zone is interpreted to encompass the high grade core of what has to date been referred to as the Eastern Breccia.
§ Incrementally higher commodity prices have been used to calculate the NSR values within the Mineral Resource estimate (US$1,700/oz Au and US$3.75/lb Cu and a USD:AUD exchange rate of 0.72 for the updated MRE, compared with US$1,600/oz Au and US$3.50/lb Cu and a USD:AUD exchange rate of 0.72 used in the March 2022 MRE) which have resulted in more Mineral Resources being reported above the NSR cut-offs, noting however that due to the high NSR value throughout most of the South East Crescent Zone this change is not considered to have resulted in a material change in the South East Crescent Zone Resources.
The increase in the Breccia Mineral Resources within the Havieron Breccia is a combination of additional drilling and the increased commodity prices.
The gold equivalent ounces per vertical metre (OPVM) of the updated MRE is presented in Figure 2.
Figure 2. Schematic 3D view looking northwest, depicting the Greatland Havieron December 2023 MRE (left hand figure) with OPVM charted to the right. The OPVM for the March 2022 MRE is also charted (light grey dashed line). Drilling intensity (grey horizontal bars) are a visual representation of the extent of drilling that has informed the MRE by vertical level (not plotted to the OPVM scale). The X axis scale (horizontal) is OPVM, while the Y axis (vertical) is plotted as relative depth in metres RL (Reduced Level).
Havieron Geology
The Havieron deposit comprises an ovoid shaped zone of variable brecciation, alteration and sulphide mineralisation (the Breccia Pipe). The mineralisation trends northwest to southeast with approximate dimensions of 650m in length by 350m in width and 1,400m in depth along a northwest orientation. Bedding of the surrounding country rocks outside of the Breccia Pipe strikes northwest to southeast and dips approximately 40° to the southwest whereas inside the breccia zone the dip steepens greater than 60° to sub-vertical.
The Breccia Pipe includes unmineralised to low-grade crackle breccia and a series of mineralised cemented breccias (Figure 3). The highest-grade breccia occurs on the margins of the Breccia Pipe and is termed the South East Crescent Zone. The Breccia Pipe also includes relatively small dioritic intrusions with brecciated contacts or wall rock clasts within the breccias. The diorite intrusions are discontinuous; however, there appears to be a strong spatial relationship between the presence and abundance of the diorite dykes and/or clasts and the presence of gold and copper mineralisation. The Breccia Pipe is intruded by a 20-30m wide, north-northeast trending, steeply dipping post mineralisation dolerite dyke.
Gold and copper mineralisation at Havieron consists of breccia, vein and massive sulphide replacement gold and copper mineralisation typical of intrusion-related styles of mineralisation. Mineralisation is hosted by metasedimentary rocks (meta-sandstones, meta-siltstones and meta-carbonate) and intrusive rocks of an undetermined age. The main mineral assemblage contains well developed pyrrhotite-chalcopyrite and lesser pyrite sulphide mineral assemblages as breccia and vein infill, and massive sulphide lenses.
Figure 3. Plan view of the Havieron deposit geological model at 4600mRL (650m below surface)
The Indicated Mineral Resource estimate includes material from the South East Crescent Zone, adjacent Breccias and a small portion (2Mt) of the Link Zone that abuts the South East Crescent. The Inferred Mineral Resource estimate is comprised of South East Crescent Zone, Link Zone and portions of the broader Breccia Zones that meet the criteria for classification.
Ordinary Kriging of 5m composites of gold and copper was undertaken into 20m x 20m x 20m blocks and re-blocked into a minimum of 4m x 4m x 4m blocks where required. The Mineral Resource model was domained utilising the geological units defining the South East Crescent Zone, Link Zone and the Cemented and Crackle Breccias. Hard boundaries were used between the South East Crescent Zone and Link Zones with the Breccia Zones and a transitional boundary of 10m was used between the Breccia Zones. Kriging Neighbourhood Analysis was used to define the search neighbourhood for gold. All grades were estimated independently of each other and composite data was capped prior to estimation. Within the Havieron Breccia complex over 99% of the resource estimation is based entirely on interpolation with less than 1% extrapolated blocks (which Greatland defines as the nearest informing composite being more than 30m away and estimated by data from fewer than 4 drillholes). The Mineral Resource model was validated via visual, statistical, and geostatistical methods.
The Indicated and Inferred Mineral Resource estimate has been constrained using appropriate drill hole data spacing parameters and geological control. Resource classification is based on a combination of geological confidence, average weighted distance and slope of regression statistics for estimated gold grades, and economic constraints (NSR). The Indicated Mineral Resource classification within the South East Crescent Zone and Link Zone is reported based on the evaluation of nominal thresholds of the average weighted distance (45m) and slope of regression (>0.6) and with blocks lying within an A$80 NSR/t shell. The Inferred Mineral Resource classification within the South East Crescent Zone and Link Zone is reported based on the evaluation of nominal thresholds of the average weighted distance (75m) and slope of regression (>0.3) and with blocks lying within an A$80 NSR/t shell.
The Indicated Mineral Resource classification within the Breccias is reported on the evaluation of nominal thresholds of the average weighted distance (30m) and slope of regression (>0.6) within an A$50 NSR/t value shell with no internal selectivity, which assumes bulk mining and therefore includes internal waste. The Inferred Mineral Resource classification within the Breccias is reported on the evaluation of nominal thresholds of the average weighted distance (75m) and slope of regression (>0.3) within an A$50 NSR/t value shell with no internal selectivity, which assumes bulk mining and therefore includes internal waste.
The NSR uses metal prices of US$1,700/oz Au and US$3.75/lb Cu, metallurgical recoveries based on block metal grade, reporting approximately 87% for Au and 87% for Cu, a USD:AUD exchange rate of 0.72, as well as treatment and refining costs, payables and royalties, similar to those applied for the March 2022 MRE.
Reasonable prospects for eventual economic extraction have been assessed through ongoing mining and processing studies which suggest that selective underground mining would be appropriate for exploitation of the South East Crescent Zone, while less selective underground mining would be appropriate for the exploitation of the mineralised Breccia Zones. There are no known environmental, social, governmental / regulatory or legal barriers to declaring this Mineral Resource.
Competent Person's Statement
Information in this announcement pertaining to the Reporting of Mineral Resources is based on information compiled and approved by Mr Michael Thomson, a Member of the Australian Institute of Geoscientists (AIG), who has more than 20 years relevant industry experience. Mr Thomson is a full-time employee of the Company and has a financial interest in Greatland. Mr Thomson has sufficient experience relevant to the style of mineralisation, type of deposit under consideration, and to the activity which he is undertaking to qualify as a Competent Person as defined by the 2012 Edition of the Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves (the JORC Code) and under the AIM Rules - Note for Mining and Oil & Gas Companies, which outline standards of disclosure for mineral projects. Mr Thomson consents to the inclusion in this announcement of the matters based on this information in the form and context in which it appears.
Independent Review of the Mineral Resource Update
SRK Consulting (Australasia) Pty Ltd has completed an independent technical assessment of the Updated Mineral Resource Estimate completed by Greatland for the Havieron deposit. As part of that assessment SRK reviewed the Resource modelling methods and parameters and found them to be reasonable and to take into consideration all of the current exploration data and levels of technical knowledge of the Havieron deposit.
SRK considers that the Mineral Resources have been reported in accordance with guidelines and principles outlined in the 2012 edition of the Australasian Code for the Reporting of Exploration Results, Mineral Resources and Ore Reserves (the JORC Code, 2012 edition).
Appendix - JORC Code, 2012 Edition - Table 1
Section 1 - Sampling Techniques and Data
|
Criteria |
Commentary |
|
Sampling techniques |
Samples are obtained from core drilling in Proterozoic basement lithologies. PQ-HQ and NQ diameter core was drilled in 6m runs. Core was cut using an automated core-cutter and half core sampled at nominal 1m intervals with breaks for major geological changes. Sampling intervals range from 0.2 - 2.0m. Cover sequences were not sampled. |
|
Drilling techniques |
The Permian Paterson Formation cover sequence was drilled using mud rotary drilling. Depths of cover typically observed as approximately 420m vertically below surface. Steel casing was emplaced to secure the pre-collar. Core drilling was advanced from the base of the cover sequence with PQ3, HQ3 and NQ2 diameter coring configuration. Core from inclined drill holes is oriented on 3m and 6m runs using an electronic core orientation tool (Reflex ACTIII or equivalent). At the end of each run, the bottom of hole position is marked by the driller, which is later transferred to the whole drill core run length with a bottom of hole reference line. |
|
Drill sample recovery |
Core recovery is systematically recorded from the commencement of coring to end of hole, by reconciling against driller's depth blocks in each core tray with data recorded in the database. Drillers depth blocks provided the depth, interval of core recovered, and interval of core drilled. Core recoveries were typically 100%, with isolated zones of lower recovery. Cover sequence drilling using the mud-rotary drilling technique does not yield recoverable samples. |
|
Logging |
Geological logging recorded qualitative descriptions of lithology, alteration, mineralisation, veining, and structure for all core drilled, including orientation of key geological features. Geotechnical measurements were recorded including Rock Quality Designation (RQD) fracture frequency, solid core recovery and qualitative rock strength measurements. Magnetic susceptibility measurements were recorded every metre. The bulk density of selected drill core intervals was determined at site on whole core samples. All geological and geotechnical logging was conducted at the Havieron site. Digital data logging was captured on diamond drill core intervals only, and all data validated and stored in an acQuire database. All drill cores were photographed, prior to cutting and/or sampling the core. The logging is of sufficient quality to support Mineral Resource estimates. |
|
Sub-sampling techniques and sample preparation |
Sampling, sample preparation and quality control protocols are considered appropriate for the material being sampled. Core was cut and sampled at the Havieron core processing facility. Half core samples of between 0.2 and 2.0 m were collected in pre-numbered calico bags and grouped in plastic bags for dispatch to the laboratory. Sample weights typically varied from 0.5 to 7kg. Sample sizes are considered appropriate for the style of mineralisation. Drill core samples were freighted by air and road to the laboratory. Sample preparation was conducted at the independent ISO17025 accredited Intertek Laboratory, Perth (Intertek). Samples were dried at 105oC, and crushed to 95% passing 4.75mm, and the split to obtain up to 3kg sub-sample, which was pulverised (using an LM5 ring pulveriser) to produce a pulped product with the minimum standard of 95% passing 106μm. Routine grind size analysis is conducted. Duplicate samples were collected from crush and pulp samples at a rate of 1:20. Duplicate results show an acceptable level of variability for the material sampled and style of mineralisation. Periodic size checks (1:20) for crush and pulp samples and sample weights are provided by the laboratory and recorded in the acQuire database. |
|
Quality of assay data and laboratory tests |
Assaying of drill core samples was conducted at Intertek. All samples were assayed for 48 elements using a 4-acid digestion followed by ICP-AES/ICP-MS determination (method 4A/MS907), which is considered to provide a total assay for copper. Gold analyses were determined by 50g fire assay with AAS finish (method FA50N/AA), which is considered to provide a total assay for gold. Sampling and assaying quality control procedures consisted of inclusion of certified reference material (CRMs), coarse residue and pulp duplicates with each batch (at least 1:20). Assays of quality control samples were compared with reference samples in an acQuire database and verified as acceptable prior to use of data from analysed batches. Laboratory quality control data, including laboratory standards, blanks, duplicates, repeats and grind size results are captured in the acQuire database and assessed for accuracy and precision for recent data. Extended quality control programmes including pulp samples submitted to an umpire laboratory and combined with more extensive re-submission programmes have been completed. Analysis of the available quality control sample assay results indicates that an acceptable level of accuracy and precision has been achieved and the database contains no analytical data that has been numerically manipulated. The assaying techniques and quality control protocols used are considered appropriate for the data to be used for reporting exploration drilling results and for use in resource and reserve estimation. |
|
Verification of sampling and assaying |
Sampling intervals defined by the geologist are electronically assigned sample identification numbers prior to core cutting. Corresponding sample numbers matching pre-labelled calico bags are assigned to each interval. All sampling and assay information were stored in a secure acQuire database with restricted access. Electronically generated sample submission forms providing the sample identification number accompany each submission to the laboratory. Assay results from the laboratory with corresponding sample identification are loaded directly into the acQuire database. Assessment of reported significant assay intervals was verified by re-logging of diamond drill core intervals and assessment of high resolution core photography. The verification of significant intersections has been completed by company personnel and the Competent Person/Qualified Person. No adjustments are made to assay data, and no twinned holes have been completed. There are no currently known drilling, sampling, recovery, or other factors that could materially affect the accuracy or reliability of the data. |
|
Location of data points |
Drill collars were surveyed using real time kinematic (RTK) GPS, with an accuracy of ±10mm E/N and ±20mm RL, for all drill holes reported. Drill rig alignment was attained using an electronic azimuth aligner. Downhole survey was collected at 6-12m intervals in the cover sequence, and every 6 to 30m in diamond drill core segments of the drill hole using single shot (Axis Mining Champ Gyro). The single shot surveys have been validated using continuous survey to surface (Axis Mining Champ) along with a selection of drill holes re-surveyed by an external survey contactor using a DeviGyro tool - confirming sufficient accuracy for downhole spatial recording. A LIDAR survey was completed over the project area in Nov 2019 which was used to prepare a DEM / topographic model for the project with a spatial accuracy of +/- 0.1m vertical and +/- 0.3m horizontal. The topography is generally low relief to flat, elevation within the dune corridors in ranges between 250-265m Australian Height Datum (AHD) steepening to the southeast. All collar coordinates are provided in the Geocentric Datum of Australian (GDA20 Zone 51). All relative depth information is reported in AHD +5000m. |
|
Data spacing and distribution |
Within the South East Crescent and Breccia zone drill hole spacing ranges from 50 to 100m, to 50 by 50m within the resource extents. Outside the initial resource boundary drill hole spacing ranges from 50 to 200m in lateral extent within the breccia zone over an area of ~2km2. The data spacing is sufficient to establish the required degree of geological and grade continuity. Significant assay intercepts remain open. Further drilling is required to determine the extent of currently defined mineralisation. Drilling intersects mineralisation at various angles. |
|
Orientation of data in relation to geological structure |
Drill holes exploring the extents of the Havieron mineral system intersect moderately dipping carbonate and siliciclastic sedimentary facies, mineralised breccia and sub-vertical intrusive lithologies. Geological modelling has been interpreted from historic and Newcrest Operations Limited (Newcrest) drill holes. Variable brecciation, alteration and sulphide mineralisation is observed within a footprint with dimensions of 650m x 350m trending in a north west orientation and over 1400m in vertical extent below cover. The subvertical southeast high grade arcuate crescent sulphide zone has an average thickness of >20m and has been defined over a strike length of up to 550m, and to over 1,000m in vertical extent below cover. Drilling direction is oriented to intersect the steeply dipping high grade sulphide mineralisation zones at an intersection angle of greater than 40 degrees. The drilled length of reported intersections is typically greater than true width of mineralisation. |
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Sample security |
The security of samples is controlled by tracking samples from drill rig to database. Drill core was delivered from the drill rig to the Havieron core yard every shift. On completion of geological and geotechnical logging, core processing was completed by Newcrest personnel at the Havieron facility. High resolution core photography and cutting of drill core was undertaken at the Havieron core processing facilities. Samples were freighted in sealed bags by air and road to the Laboratory, and in the custody of Newcrest representatives. Sample numbers are generated directly from the database. All samples are collected in pre-numbered calico bags. Verification of sample numbers and identification is conducted by the laboratory on receipt of samples, and sample receipt advise issued to Newcrest. Details of all sample movements are recorded in a database table. Dates, Hole ID sample ranges, and the analytical suite requested are recorded with the dispatch of samples to analytical services. Any discrepancies logged at the receipt of samples into the analytical services are validated. |
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Audits or reviews |
Internal reviews of core handling, sample preparation and assays laboratories were conducted on a regular basis by both project personnel and owner representatives. In the Competent Person's opinion, the sample preparation, security and analytical procedures are consistent with current industry standards and are entirely appropriate and acceptable for the styles of mineralisation identified and will be appropriate for use in the reporting of exploration results and Mineral Resource estimates. There are no identified drilling, sampling or recovery factors that materially impact the adequacy and reliability of the results of the drilling program in place at Havieron. |
Section 2 Reporting of Exploration Results
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Criteria |
Commentary |
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Mineral tenement and land tenure status |
Havieron is entirely contained within mining tenement M45/1287, which is owned by the Havieron Joint Venture participants, being Greatland Pty Ltd (Greatland) and Newcrest, a wholly owned subsidiary of Newmont Corporation (Newmont). Newcrest has previously entered into a Joint Venture Agreement (effective 30 November 2020) and Farm-In Agreement (effective 12 March 2019) with Greatland and Greatland Gold plc. Newcrest is the manager of the Havieron Joint Venture and holds a 70% interest (Greatland holds a 30% interest). Newcrest and Jamukurnu-Yapalikurnu Aboriginal Corporation (JYAC, formerly WDLAC) are parties to an ILUA which relates to the access and use of native title land for Newcrest's current operations at the Telfer mine and its activities within a 60km radius around Telfer, and following the formation of the Havieron Joint Venture, applies to Greatland and Newcrest in respect of their activities at Havieron. The mining tenement M45/1287 wholly replaces the 12 sub-blocks of exploration tenement E45/4701 (former part of the exploration tenement on which the Havieron Project is based) and was granted on 10 September 2020. |
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Exploration done by other parties |
Newcrest completed six core holes in the vicinity of Havieron from 1991 to 2003. Greatland completed drill targeting and drilling of nine Reverse Circulation (RC) drill holes with core tails for a total of approximately 6,800m in 2018. Results of drilling programs conducted by Greatland have previously been reported on the Greatland website. Drilling has defined an intrusion-related mineral system with breccia and massive sulphide-hosted higher-grade gold-copper mineralisation. |
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Geology |
Havieron is located within the north-western exposure of the Palaeo-Proterozoic to Neoproterozoic Paterson Orogen (formerly Paterson Province), 45 km east of the Telfer mine. The Yeneena Supergroup hosts the Havieron prospect and consists of a 9km thick sequence of marine sedimentary rocks and is entirely overlain by approximately 420m of Phanerozoic sediments of the Paterson Formation and Quaternary aeolian sediments. Gold and copper mineralisation at Havieron consist of breccia, vein and massive sulphide replacement gold and copper mineralisation typical of intrusion-related and skarn styles of mineralisation. Mineralisation is hosted by metasedimentary rocks (meta-sandstones, meta-siltstones and meta-carbonate) and intrusive rocks of an undetermined age. The main mineral assemblage contains well developed pyrrhotite-chalcopyrite and pyrite sulphide mineral assemblages as breccia and vein infill, and massive sulphide lenses. The main mineralisation event is associated with amphibole-carbonate-biotite-sericite-chlorite wall rock alteration. Drilling has partially defined the extents of mineralisation which are observed over 650m by 350m within an arcuate shaped mineralised zone, and to depths of up to 1400m below surface. |
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Drill hole Information |
No assay result reported in this announcement. |
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Data aggregation methods |
No assay result reported in this announcement. |
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Relationship between mineralisation widths and intercept lengths |
No assay result reported in this announcement. |
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Diagrams |
As provided. |
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Balanced reporting |
Earlier results of exploration programs conducted by Newcrest and Greatland have previously been reported. |
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Other substantive exploration data |
Nil |
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Further work |
The most recent round of growth drilling has been completed. No further drilling in planned until underground drill access has been established. |
Section 3 - Estimation and Reporting of Mineral Resources
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Criteria |
Commentary |
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Database integrity |
Data logged or received by Newcrest are stored in an SQL acQuireTM database. Assay and geological data are electronically loaded into acQuire and the database is replicated in Newcrest's centralised database system in Melbourne. In-built validation tools are used in the acQuire™ database and data loggers are used to minimise keystroke errors, flag potential errors and validate against internal library codes. Regular reviews of data quality are conducted by site and corporate teams prior to resource estimation. Final surveyed collars are checked against the original collar GPS pickup and the Lidar topographic surface. Downhole surveys are checked visually and statistically for outliers. Assay data is checked for negative, extreme, missing and overlapping samples. Below detection assay values are set to half the lower detection limit for estimation. Geological domains are reviewed against core photography, geochemistry and Corescan data and checked for overlaps and missing intervals. Data that is found to be in error is investigated and corrected where possible. If the data cannot be corrected it is removed from the data set used for resource modelling and estimation. |
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Newcrest provides Greatland with a 'data pack' approximately every 6 weeks containing new drilling data and assay results. Assay data is imported into Greatland's SQL database directly from the Laboratory assay reports, including laboratory QA/QC data. |
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Site visits |
The Competent Person for Mineral Resources visited Havieron site in November 2022, during which he inspected drilling, sampling, logging, selected drill core, the core cutting facility and is satisfied that the data and information generated and is suitable for resource estimation and subsequent reporting in compliance with the JORC Code (2012). |
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Geological interpretation |
The geology model defines several mineralised zones, including a Crescent Zone (containing the sulphide rich material in the area named the "South East Crescent Zone") and several Breccia types (Cemented Breccia (CB) and Crackle Breccia (CBX)), and several unmineralised zones (Dolerite Dyke, Calc-silicate country rocks, Permian sequence and Cover). In addition, a new sulphide rich Zone, the "Link Zone" has been defined in the lower sections of the mineral system (3750 -4000mRL). These zones are based on grouped primary logging domain codes interpreted from drill cores, mineralogical logs and assay data. Greatland has incorporated much of the previously reported Actinolite Breccia (ACB) zone into its CB and CBX zones on the bases of their similarity of spatial grade distributions and geometries, and absence of sharp contrasts in gold and copper grades between them. These zones have been modelled into 3D solids in Leapfrog Geo 6.1 using vein, intrusive and erosional implicant models. |
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The increased presence of ~northwest trending, steeply dipping diorites in the breccias corresponds to an increase in grade. Due to their dispersed nature within the breccia these diorites have not been modelled, Their impact is represented to a large extent by the choice of search neighbourhood parameters. |
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The confidence in the location and geometry of the South East Crescent Zone is generally high but decreases as the informing data becomes sparse. |
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The confidence in the location and geometry of the breccias in the Havieron Breccia zones is variable, but considered moderate in the densely drilled areas. The confidence decreases markedly as the scale is decreased. As such, this model is not a suitable basis for assessing selective mining options for these zones. |
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The confidence in the location and geometry of the Dolerite Dyke, Calc-Silicate sediments and Base of Permian is very high. |
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The interpretation is based mainly on drill hole logging and assay data as previously described in this Table. In addition, Greatland acknowledges the extensive ground work undertaken by Newcrest in identifying and interpreting the geology and agrees with the broad geological domains defined in the geological model. |
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The South East Crescent Zone is generally very well defined, and it is difficult to generate an alternative, plausible and materially different interpretation from the available data. The zone is typically intersected where expected by new drilling. Towards the base of the current drilling alternate interpretations of the South East Crescent are plausible with the Link Zone possibly being a continuation of the South East Crescent, with further drilling required to confirm this relationship. The "Link Zone" is moderately well drilled in places with the grade profile between this zone and the adjacent breccias suggesting that the domain is valid. Several estimation quality indicators (SOR, Kriging efficiencies, closest distance and average distance) suggest overall that the estimate in the Link Zone is well-informed. Currently the vast majority of this material has been classified as inferred until further work is completed. |
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The Breccia zones are reasonably well defined at a large scale but are much less well defined at the short scale owing to their low geological and grade continuity. However, it is difficult to generate alternative, plausible and materially different zones from the available data. |
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Geological controls on estimation are implicit in the domaining and the nature of their boundaries. In addition, the ~northwest striking , steeply dipping trend of the diorites is reflected in the choice of search parameters within the breccia. |
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Factors affecting continuity both of grade and geology include the change in type and intensity of brecciation and breccia fill (veining) across the Havieron system. Greatland considers the brecciation is logged and modelled in sufficient detail to be used in the estimation. |
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Dimension |
Variable brecciation, alteration and sulphide mineralisation are observed with a footprint with dimensions of 650m x 350m trending in a north west orientation and over 1100m in vertical extent below ~420m of cover. The South East Crescent Zone Mineral Resource extents are ~550m in unfolded plan section, between 5-40m true width and 1200m in vertical extent, mineralisation remains open at depth. |
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The Link zone begins at approximately the 4000mRL (1250m below surface) and has currently been defined down to 3750mRL. The Link Zone is a moderately dipping approximately 30m wide by 200m long zone of mineralisation. |
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The Breccia Mineral Resource occurs as a 50-100m sleeve marginal to the South East Crescent Zone Mineral Resource and also with pockets within the greater breccia pipe. These pockets within the core of the breccia trend from the north west near the top of the system, downwards towards the north east in the lower levels of the system and potentially connect with the Eastern Breccia material. |
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Estimation and modelling techniques |
Greatland used nominal 5m composites on a domain-wise basis for variography, search neighbourhood optimisation and estimation, with the actual composite length for each intersection adjusted to minimise the amount of 'short tails'. |
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A geostatistical review using the data up to 6 July 2023 confirmed that the gold and copper grade distributions showed that the Breccia Zones are moderately diffusive in nature, and the South East Crescent Zone is relatively weakly diffusive in nature. Even though the South East Crescent Zone is weakly diffusive in nature, Ordinary Kriging (OK) is considered an appropriate estimator given the geological setting, geological observations from the logging data, geometry of the domain and its tenor relative to the likely operating cut-off grade. |
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Composite data for gold, copper, bismuth, nickel, cobalt, iron, sulphur, calcium and magnesium were declustered using a cell-declustering approach for each domain. |
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Outlier grades were dealt with through top cutting for each variable on a domain-basis, with top-cuts generally around the 99th percentile of the declustered distribution. |
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Greatland evaluated an 'automated unfolding' method (undertaken in Microminetm) for the South East Crescent Zone that yielded robust variograms and relatively high confidence in the variogram models and estimates of gold and copper for this zone (note that the model blocks were also unfolded, with the result that parent-cell estimation could not be used for this zone). This method uses an underlying controlling surface that represents the mid-surface of the solid that was created by Greatland. |
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Greatland also used a 'trend model' method (undertaken in Microminetm) to guide the estimation of grade and density for the South East Crescent, Link Zone and Breccia zones. This approach generates a locally varying anisotropy (LVA) for each block that orients the search ellipse and variogram model to the local geometry. This approach does not explicitly unfold the composite data or block model, but does honour parent blocks during the estimation. |
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Greatland evaluation of the South East Crescent Zone via the "automated unfolding" method and trend model method resulted in an estimate with less than 1% variance in contained metal. Each method has merit but due to the limitation of the unfolding method being unable to estimate into the parent block and significant sub-celling present due to the geometry of the SE Crecent the LVA method of estimation was adopted as the preferred method for estimation. Both approaches will continue to be evaluated in future estimates. |
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A quantitative kriging neighbourhood analysis (QKNA) was undertaken on gold for each domain with the aim to maximise the slope-of-regression and kriging efficiency, whilst minimising the percentage of negative weights. Large search radii were used but with maximum number of points constraints to meet these aims. Search ellipsoids were aligned with variogram model ellipses. |
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All estimates used a hard boundary between the South East Crescent Zone and Link Zone with all other domains. A transitional boundary of 10m was used between the Cemented and Crackle Breccias to reflect the variable nature of this boundary. Only blocks 5m either side of the Cement and Crackle Breccia boundaries were allowed to utilise the transitional boundary data, the remainder of the breccia was estimated from only data within their respective domains. |
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Density was estimated by OK on a domain-wise basis Whilst density is most strongly correlated with iron (Fe) and, to a lesser extent, sulphur (S), it is also significantly influenced by the domain, with the South East Crescent domain capturing the high iron and sulphur grades, and thus density, very well. |
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Gold and copper were estimated with 2 passes, less than 0.05% of the total material classified was estimated during the second pass estimate. All other elements (bismuth, cobalt, nickel, sulphur, iron, calcium, magnesium) and density were estimated using two-passes. In addition, a higher grade bismuth domain, within the South East Crescent was defined to estimated bismuth separately. |
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Less than 1% of the Mineral Resource estimate is based on composites with a closest distance to the block of more than 30m and data from less than 4 holes, which Greatland has used to define extrapolation. These blocks are mainly on the edges of the domain. |
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Grades and density were estimated in Micromine 2023tm software. |
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The sensitivity of the South East Crescent Zone gold estimates to various top cut, search neighbourhood and variogram model parameters was assessed with variations commensurate with that implied by the resource classification. |
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There has been no production from Havieron. |
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Gold and copper are the only revenue generating products assumed to be recovered. There is sufficient metallurgical testwork to support these assumptions for the South East Crescent, Link Zone and Havieron Breccia domains. The resource does not include any by-products. |
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A parent block size of 20x20x20m (East, North, RL) with sub-blocks down to 4x4x4m has been used for all mineralised domains. This is geostatistically acceptable for the South East Crescent Zone, where the data density ranges from 50-100m However, this size is considered small for the Breccia Zones, even though parent-cell estimation was used for such. Resources in this domain have been reported using NSR-based shells that mitigate most of the detrimental effects of the block size. |
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The South East Crescent Zone is almost exclusively estimated to be above the cut-off grade and minimum stoping thickness (around 5m). Planned stope heights are well above the block vertical dimension (20m). Change-of-support tests over various block dimensions also suggest that selectivity issues are unlikely to be material for this domain. The Breccia Zones are mainly low grade and the model for such is not designed for assessing selective mining options. Change-of-support tests revealed significant differences between modelled and theoretical tonnages and grades at cut-offs well above the reporting cut-off (A$50 NSR/t). |
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Domains have principally been defined on gold grade, with copper, iron and sulphur grades also having a significant impact. Bismuth tends to be well, albeit variably, correlated with gold and so the gold domains are considered appropriate for estimating bismuth. In addition, in the upper parts of the deposit a Bismuth domain has been developed within the South East Crescent to improve the estimate in these areas. While copper is less well correlated to gold, the gold domains are considered appropriate for estimating copper. Within these domains all grades (gold, copper, bismuth, iron, sulphur, nickel, cobalt, calcium and magnesium) have been estimated independently. Given that each of these elements is assayed for each sample co-estimation, such as co-kriging, was deemed unnecessary. |
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The geological interpretation controls the resource estimates through the domaining, boundary controls between domains, and unfolding trend modelling as previously described. |
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The grade distributions for gold, copper and bismuth are strongly skewed. In addition, the very high grade composites cannot be sub-domained out with the existing density of data. As such, outlier grades were cut as previously described. |
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The estimated block grades and densities were compared to the raw and composite grades and densities using swath plots, cross-sections and statistical analysis. |
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There is no reconciliation data for Havieron. |
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Moisture |
All tonnages are calculated and reported on a dry tonnes basis. |
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Cut-off parameters |
As Havieron is a multi-element deposit, a Net Smelter Return (NSR) cut-off is adopted. The generic NSR formula is as follows: |
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NSR (AUD/t processed) = (Gold Price * Ore Gold Grade * Gold Recovery * Gold Payability) + (Copper Price * Ore Copper Grade * Copper Recovery * Copper Payability) - (Treatment, Refining, Freight, Insurance and Selling Costs) - Penalties - Royalties |
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The NSR calculation for Mineral Resources takes into account revenue factors, metallurgical recovery assumptions, transport costs, refining charges, penalties and royalty charges at a gold price of US$1,700 per ounce, copper price of US$3.75 per pound (US$8,265/t) and an USD:AUD exchange rate of 0.72. Commodity prices and exchange rate forecasts were based on combination of peer pricing analysis and broker consensus forecast data. |
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The nominal cut-off value for resource reporting depends on the style and geometry of mineralisation with the South East Crescent Zone being amenable to stoping, whereas the Breccia Zones require a less selective (and lower cost) mining method. The cut-offs were derived after incorporating mining, haulage, processing and general and administration costs. |
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The marginal cut-off for SLOS ("sub-level open stoping", for the South East Crescent Zone) is estimated at A$80 NSR/t, and accounts for mining, haulage, processing and general and administration (G&A) costs, which are based on the PFS Economic Evaluation average Life-of-Mine (LOM) Costs. |
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The Mineral Resource was defined based on a threshold of A$80 NSR/t within the South East Crescent Zone. The vast majority (>90%) of the estimated South East Crescent Zone material reports above the A$80 NSR/t, as such domaining all material below this cut-off is not practicable. Areas of South East Crescent Zone material that had a higher frequency of blocks below A$80 NSR/t were removed from the classification and grouped with the adjacent Breccia domains. |
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The cut-off for the Breccia Zones (assuming SLC or "sub level caving") is estimated at A$50 NSR/t, and accounts for mining, haulage, processing and G&A costs, which are based on the PFS analysis. |
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For the Breccia Mineral Resources, a smoothed shell was generated in Leapfrogtm Version 2023.1 based on a threshold of A$50 NSR/t and includes internal below value cut-off blocks and excludes isolated above cut-off blocks. As the Breccia Resources are consider non-selective bulk mining domains all sub-economic material within the final A$50 NSR/t shell was classified to represent the non-selective nature. |
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Both the South East Crescent Mineral Resources and Breccia Mineral Resources represent the limit of reasonable prospects of eventual economic extraction. The A$80 NSR/t cut-off for South East Crescent Mineral Resources and A$50 NSR/t cut-off for Breccia Mineral Resources are based on the current understanding of the Havieron deposit and other benchmarked operations. |
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Greatland used smoothed NSR shells to define its Breccia Resources and this results in some material below the nominal cut-off being included in the resources. The following table shows the total and proportion of the Mineral Resource tonnages and Contained Metal above and below the nominal cut-off NSR each Domain/Lode/category combination. A key observation is the NSR indicator shells process in Leapfrogtm brings in additional lower NSR material to encapsulate higher grade material if the outcome is warranted, in a sense building in some degree of expected dilution for that material.
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Mining factors or assumptions |
The PFS showed that the South East Crescent Zone and immediately adjacent diluent material is amenable to mining by sub-level open stoping (SLOS) with minimum mining dimensions of 5mW x 15mL x 25mH. The updated resource model supports that finding. |
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The PFS suggests that the Breccia Zones may be amenable to, and require the lower costs of, bulk mining methods such as sub-level caving (SLC). SLC is likely to require minimum mining dimensions of 80mW x 100mL x 100mH. The Mineral Resources assume there will be no significant permanent pillars in the resource volume, although it is possible that a pillar will need to be left between the paste-filled South East Crescent Zone stopes and the Breccias, and which will be accounted for during Ore Reserve estimation. |
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Metallurgical factors or assumptions |
It is anticipated that Havieron ore will be processed on a campaign basis through the Telfer Treatment Plant circuit at a throughput of approximately 3 Mtpa. It is anticipated that metal will be recovered through conventional flotation to produce a copper/gold concentrate and a gold doré through a newly installed flotation tails carbon-in-leach (CIL) circuit. The technology associated with the ore processing is conventional and the flowsheet is similar to that utilised by other operations. |
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Metallurgical recovery assumptions are based on detailed analysis and laboratory flotation and leach test work completed on 47 geo-metallurgical variability samples during the Havieron Concept Study (2020) and Stage 1 PFS (2021) with good spatial coverage of the South East Crescent Zone Domain. Another 38 geo-metallurgical variability samples have been tested during the Feasibility Study increasing the special coverage. Of the 87 samples, 29 samples are located in the Breccia Zones, 56 samples are located in the South East Crescent Zone Domain. Based on these samples, metallurgical recoveries for gold are anticipated to average approximately 87% and recoveries of copper are expected to average approximately 87% throughout the life of the project. Note that Greatland does not have any metallurgical testwork results for the Eastern Breccias and it is assumed that they have similar metallurgical properties to their corresponding Breccias. |
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Environmental factors or assumptions |
Detailed environmental studies have been undertaken in the Project area and include flora and vegetation, fauna, subterranean fauna, waste rock characterisation, soil and landform study, surface hydrology assessment, a basic hydrogeological assessment and a greenhouse gas emissions study. |
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The Project has been designed to recognise biodiversity values and, through consultation with Martu and their native title corporation (JYAC), minimise the impacts to sites and landscapes of cultural significance. The footprint for the Project has been minimised through the use of existing tracks and areas of disturbance, as well as utilising the existing Telfer mine infrastructure to process the ore and dispose of the tailings material. |
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Waste rock characterisation has been undertaken and shows that it contains material which has potentially acid forming (PAF) and metalliferous drainage, in addition to dispersive or saline material. The portion of PAF material is less than 1% of total waste volumes. Waste dumps have been designed for the life of mine that have incorporated cells to safely encapsulate the PAF material. The waste dump is to be located near the boxcut to minimise haulage distance and considering the local surface terrain and environmental and cultural aspects. |
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A staged approach for approvals is being undertaken, with Stage 1 currently approved, which has allowed the development of the boxcut, decline and service corridor. These approvals also allow for a waste rock dump, evaporation ponds and supporting infrastructure such as offices and workshops. |
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Stage 2 approvals are expected to consist of a SLOS underground mine, permanent infrastructure corridor, associated infrastructure and changes to Telfer mine approvals to accept Havieron tailings in existing tailings storage facilities. |
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Bulk Density |
Havieron has an extensive database of bulk density measurements based on the Archimedes method (water immersion) of 10-20cm samples taken at 10-50m intervals down the hole. Whilst the geology, and thus density, can change rapidly down the hole, the number of measurements means that the data set is likely to be representative for the purposes of this estimate. |
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Most of the core in the mineralised zones is very competent and of low to negligible porosity. |
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Bulk density is estimated into blocks using OK on a domain-specific basis. The variability of density is relatively low in the Breccia zones and the scope for an estimation related bias is very low, even at the local scale. The variability of density in the South East Crescent zone is higher and, whilst local estimation-related biases may occur, it is unlikely that a significant global bias exists. |
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Classification |
Resources preliminarily classified on the basis of the quality and quantity of data, the geological and grade continuity, and the confidence in the gold grade estimates. Data quality is implicitly accounted for by excluding unreliable data from the estimate. |
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Confidence in the estimate was initially assessed using the 'Slope-of-regression', 'Average Distance to informing composites', 'Closest Distance to informing composites', 'Kriging Efficiency', 'Number of Informing Drill Holes', and 'Number of Informing Composites' statistics stored during estimation. The schema was then simplified to only account for the 'Slope-of-regression' and 'Average Distance for informing composites' statistics. Shells based on these two statistics were computed at various thresholds for each of the domains. The chosen nominal parameters were: |
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Domain |
Category |
Slope |
Average Distance |
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CRS |
Indicated |
>0.6 |
<45m |
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CRS |
Inferred |
>0.3 |
<75m |
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Breccias |
Indicated |
>0.6 |
<30m |
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Breccias |
Inferred |
>0.3 |
<75m |
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This approach led to some blocks not meeting these criteria to be included and some meeting these criteria to be excluded from the shells. Furthermore, some edges were manually trimmed to ensure continuity of classification. |
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The final classification then considered the 'reasonable prospects of eventual economic extraction', and specifically the mineability by the proposed method, the recoverability by the proposed processing method, and the likelihood that the resource would be above the cut-off. |
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Several early drill holes were deemed to be of low reliability and were excluded from the estimation. All remaining data are considered suitable for the purposes of resource estimation. |
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Geological and grade continuity in the South East Crescent Zone can reasonably be assumed in most places, and implied elsewhere. When combined with the density and orientation of data, as well as the likelihood and impact of any misestimation, this supports the assigned Indicated (assumed) and Inferred (implied) resources classification. |
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Geological and grade continuity in the Breccia zones is typically much lower. However, the data density is moderate-high in the southern parts of the Breccias adjacent to the South East Crescent Zone and geological and grade continuity can be reasonably assumed. As such, some of this material has been assigned as Indicated resources. The remainder of the Breccia Zone has been assigned as Inferred resources as the continuity of geology and grade can only be implied from the available data. The confidence in the estimates of the Breccia zones decreases rapidly as the cut-off is increased and significant misrepresentation of tonnages, grades and location above elevated cut-offs in this model is likely, and so the classification is strictly only applicable at the reporting cut-off A$50 NSR/t. |
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The classification appropriately reflects the views of the Competent Person. |
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Audits or reviews |
SRK Consulting (Australasia) Pty Ltd has completed an independent technical assessment of the 2023 Mineral Resource estimates completed by Greatland for the Havieron gold and copper deposit. As part of that assessment, SRK reviewed the resource modelling methods and parameters and is of the opinion that they are reasonable and take into consideration all of the current exploration data and levels of technical knowledge of the Havieron deposit. SRK considers that the Mineral Resources have been reported in accordance with guidelines and principles outlined in the 2012 edition of the Australasian Code for the Reporting of Exploration Results, Mineral Resources and Ore Reserves (the JORC Code, 2012 edition). |
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Discussion of relative accuracy / confidence |
Greatland has conducted Change-of-Support studies using the Discrete Gaussian Method for the South East Crescent Zone and Breccia Zones. These studies revealed that the estimates for the South East Crescent Zone are robust within the context of the likely operating cut-off value. The studies also revealed that the estimates for the Breccia Zones are reasonable at the likely operating cut-off (A$50 NSR/t), but this accuracy rapidly diminishes as the cut-off is increased. |
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There is no historical production from Havieron. |
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