Tumblegum South Gold Project
The Tumblegum South Project is located 40km south, southeast of Meekatharra, and 1km west of Meekatharra-Sandstone Rd, approx. 3km to the east of the ‘Star of the East’ historical mine, and 1km south of the old Gabanintha Gold Mine.
The Tumblegum South gold deposit is considered the southern extension of mineralisation encountered in the Gabanintha gold mining pits operated by Dominion Mining Ltd between 1987 and 1992.
The Tumblegum South Project consists of a granted Mining Licence M51/888 and hosts a gold Mineral Resource of 616,000 tonnes @ 2.28g/t Au for a total of 45,000 ounces of contained gold and includes an Indicated Mineral Resource of 337,000 tonnes @ 2.52 g/t Au for 27,000 Oz gold.
A Scoping Study was completed in December 2023 and subsequently updated in April 2024 in light of a sustained increase in the gold price above the range quoted in the initial Scoping Study and included updated processing and transport costs after discussions and feedback with operators and interested parties in the area.
The positive results of this Updated Scoping Study provide a basis to refine material inputs and enhance project economics for the Tumblegum South gold deposit.
Figure 1: Location map and relevant infrastructure in the area.
Figure 2: Regional geology
The geological setting is interpreted as the eastern side of a syncline, within a mafic/ultramafic volcanic suite, overlain with BIF/sediments/felsic rocks. This area has undergone intense folding and shearing, with the major shear structure dubbed the “Gabanintha Shear”. This pattern of folding and shearing along the contact is seen throughout the region.
Observations from Gold Resource Review
Current (INFERRED and INDICATED) Resource Model
Figure 3: Main vein sets and cross-section of thrust structural interpretation with initial (2019) RC drilling.
Positive Updated Scoping Study for Tumblegum South Gold Project
Project sensitivities were examined for a range of gold prices demonstrating that Project economics are robust with positive outcomes returned for gold prices ranging from AUD$2,000 to AUD$4,000 per ounce.
A Base Case at AUD$3,400 per ounce gold price was used to assess the components of Inferred and Indicated Mineral Resources. The range of the Updated Production Target outlined via pit optimisation at the Base Case for a range of toll treatment and road haulage costs is set out below:
Key Study Outcomes and Assumptions
The Updated Scoping Study is based on the May 2023 Tumblegum South mineral resource estimate described in Star’s announcement to the ASX on 29 May 2023[1]. The resource model was prepared by Entech, an independent competent person in accordance with the JORC Code (2012) and includes estimates classified as Indicated and Inferred. Orelogy’s study included generating an optimal pit geometry utilising Whittle optimisation software.
Based upon the resource estimate model, slope parameters and the cost structure applied, the Updated Production Target outlined via pit optimisation at gold prices AUD$3,000 to AUD$3,800/oz, ranges from approximately:
Approximately 60-65% of the total Updated Production Target resulting from the Updated Scoping Study is based on Indicated Mineral Resources, and approximately 35-40% is based on Inferred Mineral Resources. There is a low level of geological confidence in Inferred Mineral Resources and there is no certainty that further drilling will result in the determination of Measured or Indicated Mineral Resources or that the Updated Production Target will be realised. Although some of the Inferred Mineral Resources occur at shallow depths, there is sufficient, easily mined and readily accessible Indicated Mineral Resources within the optimum shell to enable stockpiling of at least half of the Inferred Mineral Resources to be deferred to the latter processing (starting after month 12 or later) of the Project. This will mitigate the risk to the project as it can be grade controlled and resampled prior to processing.
No allowance was made for capital or start-up costs in the optimisation analysis stated above. The capital and start-up costs are comprised of the costs associated with, but not limited to mobilisation, site establishment, pre-mining earthworks, access and haulage road and demobilisation. These costs have been estimated for the purposes of the Updated Scoping Study at approximately $1.1M and can be represented as a range from $0.7M to $1.5M to reflect the accuracy of cost parameters used in the study which is +/- 35%. To estimate working capital requirements, an approach was taken to produce mine schedules for the range of options at the Base Case gold price at AUD$3,400 per ounce, was evaluated using the same cost and revenue assumptions, with the maximum cash drawdown allocated as working capital.
Based upon this approach the total working capital requirements were estimated to range from approximately $1.0M to $2.4M, with $1.7M for the Mid cost option. The pits for each option are estimated to have a mine life of less than 15 months with maximum cash drawdown occurring between months 3 to 5.
To achieve the range of outcomes indicated in the Updated Scoping Study, funding of the order of approximately $2.8M (based on a range of between $1.7M to $3.9M) will likely be required for capital, start-up costs and working capital requirements.
Figure 4: Tumblegum South Gold Deposit Optimised Pit Plan Over Geology.
Figure 5: Tumblegum South Gold Deposit Cross Section Through Optimised Pit (refer Figure 4).
[1] See Star Minerals Limited (SMS) ASX announcement dated 29 May 2023 ‘Tumblegum South Mineral Resource Update’
