Theta (Open cut) Project

On 16 May 2019, the Company announced its first mining Reserve and released its very first Feasibility Study based on this Reserve.

The global Mineral Resource includes Theta Gold’s core project, the Theta Project, located next to the historical gold mining town of Pilgrim’s Rest, in Mpumalanga Province, some 370km east of Johannesburg.  

A detailed summary of the Feasibility Study (May 16, 2019) may be viewed via the ASX Announcement link below:


A Positive Feasibility Study

Open Cut Theta Project – startup Feasibility Study Highlights

  • Total gold recovered over 5 years 201Koz @ 40Kozpa
    • Initial 2 years from Theta Hill (incl. Browns) to recover ~91.05Koz (recovered grade 2.81g/t Au) at 45.53Kozpa
  • Average All-in-Sustaining Cost USD764/oz
  • 9 month construction timeline & plant upgrade to 500ktpa
  • Post-tax cumulative undiscounted EBITDA over LoM USD99.6m
    • 1.2 years payback period
    • Post-tax Internal Rate of Return 65.1%
  • USD29.2m Peak funding  requirement (incl. new mill & elution circuit)


The positive Feasibility Study for the Theta Project, which includes the Columbia Hill deposit and part of the Theta Hill deposit within Mining Right 83 (“MR83”), confirms the project economics and its commercial viability.

Significantly, the study places Theta Project in the bottom quartile for costs (AISC USD764/oz potential); making the mine when in production potentially one of South Africa’s lowest cost gold producers. 

Additionally, with a head grade of over 2.7g/t Au to mill, and high metallurgical recoveries (91.6%), the results for the project are robust for shallow pits with an average depth of 70m to 90m.

Significantly, the Feasibility Study indicated a peak funding requirement of less than USD30m and a short 9 months of construction/refurbishment period post permitting and financing, with permitting approvals already underway.

The Feasibility Study was limited to Indicated Resources within Mining Right 83 (“MR83”) – only 16.7% of existing Open-cut resources. The initial Ore Reserve within MR83 is 205Koz Au (2.31Mt @ 2.76g/t Au) and the Feasibility Study was also limited to the existing fully approved 2.5Mt Tailings Storage Facility (“TSF”) where the company is in progress to apply for additional ground to enable potential plant/production expansion.

The open cut mineral resource across MR83 and MR341 is 879.6 Koz Au (10.1Mt @ 2.7g/t Au) which provides significant potential to define additional ore reserves to ramp-up production and extend mine life. The resources remain open to the south and southwest and the Company expects to increase the Probable Reserve as it expands the project.

Drill Hole Location Plan with Future Drilling

Figure 2: Aerial view (West to East) of CIL Plant and Theta Hill


Ore Reserves – Theta Project


  1. The Ore Reserve cut-off grade is 0.4 g/t.
  2. Totals in the Ore Reserve may not add-up due to rounding.
  3. Mineral Resources are for MR83 only and excludes MR341.
  4. No Inferred Mineral Resources are included in the Ore Reserve.


The Mineral Resource to Ore Reserve conversion requires application of appropriate factors which would account for any changes to the Mineral Resources (Figure 4) in the life of mine plan as a result of mining the ore. As part of the technical studies the potential ore loss and dilution to the Mineral Resources was determined and applied to the resources available for conversion to Ore Reserves. The ore loss reduces the tonnage and content, while the dilution would add additional tonnage with no gold content. Note ore reserve included previously undiscovered reefs (Bevetts and Shale Reef).


Feasibility Study Inputs and Derivation

The Theta Project Feasibility Study is based on the following key input parameters:-

  • The Mineral Resources were estimated and compiled by Minxcon (Johannesburg);
  • A Probable Ore Reserve and detailed monthly mining and processing schedule, derived from primarily Indicated Mineral Resources and a small portion of Inferred Mineral Resources (<7% of content), produced by Minxcon after the application of mining parameters, mining and processing costs from in-country contractors, processing inputs and geotechnical pit design considerations.
  • Geotechnical inputs and parameters for pit designs from Open House Management Solutions (Pty) Ltd  (Rustenburg);
  • Process engineering design, capital and operating costs by METS South Africa (Pty) Ltd  (Pretoria);
  • Metallurgical recovery inputs based on test work by SGS South Africa and interpreted by ENC Minerals (Pty) Ltd.
  • Tailings storage facility design, capital and operating costs by Tailex Management Services (Pty) Ltd
  • Waste, residue and water storage designs by Minxcon;
  • Rehabilitation provision by Globesight (Pty) Ltd;
  • Other cost inputs, i.e. labour, overheads, outsourced services and environmental and socio-economic costs by owner’s team; and
  • Financial Model compiled by Minxcon.