-tons per annum of copper equivalent per annum. The size of the resources, the optionality exists to expand from there. Our portfolio, we've got predominantly copper but also a lot of zinc. We've got a lot of precious in there as well. This commodity diversification has certainly been a benefit recently with the run-up in precious metals prices. A little more detail now on Golden Grove. Golden Grove is a world-class VMS system. It's got 63 million tons in the mineral resources. The asset started production in 1990, has had over three decades of life to date. With that 63 million tons still in the resource, we've got lots of potential bringing our two highest grade ore sources into the mine plan. We've had substantial investment on the surface as well.
With the triple sequential flotation, the paste plant, ventilation, and most recently, a long-term tailings storage facility. Gossan Valley on the right. Nearing that investment, from the end of 2026, we expect reduction in capital expenditures, ramp up of mining from these high-grade ore sources. Xantho Extended, Oizon, Gossan Valley all coming into the mine plan. This slide shows the positive contribution these ore sources are expected to have on mill throughput and mill grade. From the back end of 2026, Xantho Extended and Oizon high-grade ore sources at Gossan Hill both ramping up. Gossan Valley, new mining front, production flexibility and relatively shallow, independent. An optimized and flexible mine plan for Golden Grove, which will deliver more tons, higher grade, supporting metal production growth and free cash flow.
You can see we're already on a journey of improved operational and financial outcomes at Golden Grove. From 2023- 2025, Golden Grove delivered a 345% increase in EBITDA and 11% reduction in unit costs on the backdrop of an inflationary environment. The asset has had a decades-long history of mine life extensions and ongoing resource extension drilling continues to provide confidence that Golden Grove will be operating for decades to come. Every intercept on this page has been released in the last 12 months, all of them resource extension intercepts. Lots of high-grade copper and zinc, extending existing ore bodies and adding mine life and lots of high-grade gold and silver intercepts, which are pretty handy byproducts, particularly at the moment. Too many phenomenal intercepts to go through each one of them, but a couple to call out, particularly high up in the mine at Tryall.
Up to 20 m and up to 2.8% copper at an ore source that is very shallow in the mine, short trucking distances, and the existing development allows incorporation into our near-term mine plans. The drilling also continues to grow inventory at Hougoumont Extended and Oizon, where we see that those ore bodies are coming together and converging at depth in one large mineralized system. 30 m at 17% zinc, 15 m at 2.6% copper. This will enable future mining cost efficiencies via the shared infrastructure as mining progresses in this area. Lots of high-grade resource extension results coming from the exploration program, which gives us confidence on mine life extensions for many years to come. You can see here the 30+ year history of growth at Gossan Hill and Scuddles.
Now for the first time in 30 years, we're opening a new mining front with Gossan Valley, which remains completely open at depth. Once underground, we look forward to resource extension drilling and aiming to build on Golden Grove's long history of exploration success. We see a bright future at Golden Grove. We're nearing the end of this significant investment phase to enable the mining of high-grade ore sources. From the end of 2026, we expect reduction in capital expenditures, progressive ramp up of mining from the high-grade ore sources, Xantho Extended, Oizon and Gossan Valley. The site still has a lot of exploration potential that we're looking to unlock. Now to Capricorn Copper, where the size of the prize is significant.
64 million tons in mineral resources, 1.2 million tons of contained copper, established surface infrastructure, established underground development, and all in the prolific Mount Isa Inlier. Lots of exploration upside from that. We've got a low capital intensity brownfields restart project. Cap Copper is expected to double our group copper metal production and contribute to significant EBITDA. In 2021 and 2022, when the last two full years of operation at Capricorn Copper, the asset delivered AUD 110 million and AUD 66 million of EBITDA respectively, and that was at AUD 4 per pound copper prices. It's expected to produce at very strong all-in sustaining cost margins at current prices beyond AUD 6 per pound. The team have made excellent progress to restart the production of the asset. Since I joined the business in mid-2024, felt like all I talked about was water for Cap Copper for a long time.
Water is no longer the impediment to a restart of production. Moving to a tailings storage facility, that is now the critical path. I'm very pleased with the work the team have done. During what was a heavy 2025, 2026 wet season, the team were able to dramatically reduce the site water levels. Water no longer the impediment. It means we can move on to other things. The tailings storage facility, that is critical path. We're working towards a response to the regulator's request for information in the September quarter. We are planning for success. We've kicked off the definitive feasibility study, which will accelerate the production once we receive the tailings permit. We see a bright future at Capricorn Copper. It's in a Tier- 1 location. It's got a large copper metal endowment.
It's got a low capital intensity pathway to up to 30,000 tons per annum of copper production. Lots of geological upside, which will enable future expansion of resources and production. Why invest in 29Metals? Globally, copper supply is challenged. New mines are becoming harder to find, lower grade and harder to mine. As the world electrifies, we're going to need a lot more copper. We've got a lot of copper, over 2 million tons in mineral resources, two Australian-based assets, both with long life potential and significant geological upside. The team are focused on leveraging this position, delivering safe, reliable production and delivering on our growth plans. At 29Metals, we say it's worth a look. If you've already had a look, it's worth another look because it's very different going forward than looking back. Thank you