Looks like the question was something along the lines of “given everything we know about Telfer gold mine what size of resource in the West Dome Deeps target can be inferred from these preliminary results?” ;
Greatland Gold recently announced results from their maiden underground drilling campaign at the West Dome Underground target, part of the Telfer gold-copper mine in Western Australia, on February 20, 2025. This discovery is significant as it confirms high-grade gold and copper mineralization beneath the existing West Dome open pit, potentially extending the mine's life and adding to its resource base. However, estimating the exact number of additional gold ounces this discovery might contribute requires careful consideration of available data and some assumptions, as no definitive resource estimate has been provided yet for this specific zone.
Yesterday’s question about the remaining gold ounces at Telfer likely refers to the broader Telfer operation, which includes open pit and underground mining areas like Main Dome, West Dome, and stockpiles. As of December 31, 2024, Greatland reported significant stockpiles at Telfer, with an estimated 10.9 million tonnes of run-of-mine ore containing approximately 247,000 ounces of gold, plus additional low-grade stockpiles estimated at 19 to 23 million tonnes, potentially containing another 250,000 to 300,000 ounces (based on typical low-grade estimates of 0.3-0.5 g/t). This suggests a total of around 500,000 to 550,000 ounces in stockpiles alone, with additional resources in active mining areas like Main Dome Underground, which has historically produced over 3.1 million ounces and continues to operate.
The new West Dome Deep zone (referred to in your question as West Dome Deep, likely the same as the West Dome Underground target in Greatland’s announcement) is an underground exploration target accessed via a drill drive from Main Dome. The drilling results indicate mineralization over a 700-meter strike length, with 16 of 19 drill holes yielding an average intercept of 23.2 meters at 2.95 g/t gold and 1.07% copper (equivalent to 4.23 g/t gold when factoring in copper value, using a gold equivalent formula). Standout intercepts include 14.3 meters at 9.06 g/t gold and 8.57% copper, suggesting pockets of very high-grade material. Importantly, the mineralization remains open along strike and at depth, indicating potential for further expansion.
To estimate the potential additional ounces, we can make a rough calculation based on the drilling data and geological similarities to Main Dome Underground, which Greatland notes shares the same key features. Main Dome has produced over 3.1 million ounces from 75 million tonnes of ore (averaging around 1.3 g/t gold historically, though higher-grade zones exist). For West Dome Underground, the current drilling covers 700 meters of strike, but the full extent is unknown. If we assume a mineralized zone of 700 meters strike, 200 meters width (a reasonable estimate based on typical underground deposits like Main Dome), and 100 meters vertical depth (conservative, as it’s open at depth), that’s a volume of 14 million cubic meters. With a density of 2.7 t/m³ (standard for this type of rock), this equates to about 37.8 million tonnes.
Applying the average grade from the drilling results (2.95 g/t gold), this could yield approximately 3.58 million ounces of gold (37.8 million tonnes × 2.95 g/t ÷ 31.1035 g/oz). Adding the copper at 1.07% (with a copper price of ~$9,000/t and gold at ~$2,650/oz, copper adds roughly 0.4 g/t gold equivalent), the total gold equivalent could approach 4.8 million ounces. However, this is a maximum theoretical estimate. In practice, not all mineralized material becomes an economic resource—factors like mining dilution, recovery rates (typically 85-90%), and economic cutoffs (likely 1-2 g/t for underground mining) reduce the figure. A more conservative estimate, assuming only 50% of the volume is economically viable (18.9 million tonnes), suggests around 1.8 million ounces of gold, plus copper value boosting it to perhaps 2.4 million gold equivalent ounces.
Greatland has not yet defined a maiden Mineral Resource estimate for West Dome Underground, and their next steps include a second phase of drilling to refine the size and grade. Given the early stage and open-ended nature of the deposit, a realistic range for additional ounces might be 1 to 3 million ounces of gold, with copper adding further value (potentially 0.5-1 million gold equivalent ounces). This aligns with Greatland’s optimism about extending Telfer’s mine life and the geological parallels to Main Dome.
In summary, while it’s too early for precision, the West Dome Underground discovery could add an estimated 1 to 3 million ounces of gold to Telfer’s inventory, with copper enhancing the total value, potentially bringing it to 1.5 to 4 million gold equivalent ounces depending on further exploration and economic factors. This is a preliminary estimate, and actual figures will depend on future drilling and resource modeling. For comparison, Telfer’s current operational resources and stockpiles are in the 0.5-1 million ounce range, so this could significantly boost the mine’s longevity. Keep an eye on Greatland’s upcoming updates for a clearer picture!
