OceanaGold Reports Mineral Reserves and Resources for the Year Ended 2023

VANCOUVER, BC, Feb. 21, 2024 /PRNewswire/ – OceanaGold Corporation (TSX: OGC) (OTCQX: OCANF) (“OceanaGold” or the “Company”) is pleased to provide its Mineral Reserves and Mineral Resources (“R&R”) statement for the year-ended December 31, 2023.

Gerard Bond, President and CEO of OceanaGold, said “I am pleased to share the updated Mineral Reserves and Resources estimates for the Company, including at Haile, where we were able to increase Horseshoe reserves and declare an initial reserve estimate of 380,000 ounces at Palomino. The opening and successful delivery of ore from the Horseshoe underground at Haile last year was a pivotal milestone for the Company. With growth in the Horseshoe reserve and the addition of Palomino to reserves, the projected longevity and profitability of the Haile mine is strengthened. 

Additionally, I am delighted by the increase in Indicated resources at Wharekirauponga in New Zealand, which now exceeds one million ounces and with a grade increase to 15.9 g/t, demonstrating how truly exceptional this deposit is. Our updated reserves and resources estimates continue to provide a strong base for organic growth in the coming years and I am excited about what our exploration programs will bring in 2024 and beyond.”

Highlights

• Total Mineral Reserve additions of 0.69 Moz before mining depletion and adjustments 
• Total Measured and Indicated Mineral Resource additions totalled 1.12 Moz
• Initial Mineral Reserves of 4.0 Mt @ 2.91 g/t Au for 0.38 Moz declared at Palomino at Haile
• Increase in Mineral Reserves to 3.8 Mt @ 4.23 g/t Au for 0.52 Moz at Horseshoe at Haile
• Increase in Measured and Indicated Mineral Resources at Didipio of 0.11 Moz
• Increase in Indicated Mineral Resources to 2.0 Mt @ 15.9 g/t Au for 1.01 Moz at Wharekirauponga
• Increase in Indicated Mineral Resources by 0.15 Moz at Martha Underground at Waihi
• Decrease in Mineral Reserves at Macraes by 0.5Moz, reflecting the removal of Round Hill  

Mineral Reserves

The Proven and Probable Mineral Reserves estimates as at December 31, 2023 are presented in Table 1 below.

Table 1: Proven and Probable Reserves as at 31 December, 2023

• Mineral Reserves are defined by mine designs based upon metal prices of US$1,500/oz gold, US$3.00/lb copper and US$17/oz silver. New Zealand reserves use 0.70 NZD/USD exchange rate.
• Reported estimates of contained metal are not depleted for processing losses.
• For underground reserves, cut-offs applied to diluted grades.
• For Haile Open Pit, the primary cut-off grade is 0.5 g/t Au whilst oxide material is assigned a 0.6 g/t Au cut-off grade.
• For Haile Underground, the cut-off is 1.87 g/t Au, with adjacent lower grade stopes included in the reserves based on an incremental stope cut-off grade of 1.74 g/t Au.
• For Didipio, gold equivalence (AuEq) is based upon the presented gold and copper prices as well as processing recoveries. AuEq = Au g/t + 1.37 x Cu%.
• For Didipio, the 18.0 Mt open pit stockpile inventory includes 5.3 Mt of low-grade stocks mined at an approximate 0.27 g/t AuEq cut-off.
• For Didipio Underground, incremental stopes proximal to development already planned to access main stoping areas are reported to a lower cut-off of 0.76 g/t AuEq.
• For Macraes Underground, Frasers Underground cut-off is 1.28 g/t Au whilst Golden Point Underground cut-off is 1.35 g/t Au.
• For Martha Underground, the cut-off for previously unmined stoping areas is 2.6 g/t Au, increasing to 3.1 g/t Au for stoping areas in close proximity to remnant workings.

Mineral Reserves increased year-over-year at Haile, due to increases in the Haile underground, where additions were made at Horseshoe and the first Mineral Reserve estimate for Palomino was declared. Further details, including a detailed mine plan for Haile, is expected to be released in an updated technical report in accordance with National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-101”) by March 31, 2024. The technical report will include both Palomino and Horseshoe underground mines, with first ore from Palomino expected in 2027. The Company is also advancing a trade-off study on the potential option to mine Ledbetter phase 4 from underground as compared to the current plan to mine as an open pit. If the underground option is deemed to improve the economic value of the mine, this could result in the removal of lower-margin Mineral Reserves at Haile.

The Macraes Future Options work was completed in 2023, as outlined in the 2022 Mineral Reserves and Resources statement. The work concluded that the Round Hill Open Pit did not generate sufficient economic return on capital, and therefore was removed from Mineral Reserves in 2023, which resulted in a 0.5 Moz reduction in reserves at Macraes. This was partially offset by the reserve additions mentioned above that contributed to a consolidated 0.31 Moz decrease in Mineral Reserves across the Company. An updated NI 43-101 technical report for Macraes is expected to be completed by March 31, 2024. The team is also focused on identifying potential additional ore sources that could extend mine life at gold prices above the current $1,500/oz Mineral Reserve price assumption.  

Mineral Resources

Measured and Indicated Resources

The Measured and Indicated Mineral Resource estimates (inclusive of Mineral Reserves) as at December 31, 2023 are presented in Table 2 below.

Table 2: Measured and Indicated Resources as at 31 December, 2023

• Mineral Resources include Mineral Reserves. There is no certainty that Mineral Resources, not included as Mineral Reserves, will convert to Mineral Reserves.
• All…