This Mine Shouldn’t Exist… But It’s Worth Billions

#goldmining #gold #australia Deep beneath the quiet farmland near Heathcote lies one of the most unusual and valuable mineral deposits in Australia—the Costerfield Mine. This underground gold antimony mine has produced over 500,000 ounces of gold alongside significant quantities of antimony, making it one of the highest-grade and most unique gold deposits in the country. At today’s gold price of over $6,800 AUD per ounce, this small, narrow vein system has generated billions of dollars in value, all from ore bodies that are often less than a metre wide. Unlike large open pit gold mines, the Costerfield deposit is mined underground by following extremely narrow, high-grade quartz-stibnite veins through the rock. These gold-bearing veins can extend for over a kilometre, yet remain incredibly thin, forcing miners to extract ore with precision and accuracy. This makes Costerfield one of the best examples of high-grade underground gold mining in Australia, where geological structure controls everything—from ore distribution to mining methods. Geologically, the Costerfield gold antimony deposit is located within the Lachlan Orogen, one of Australia’s most important gold-producing regions. The deposit formed from hydrothermal fluids released during metamorphism of ancient sedimentary rocks, which transported gold, antimony, arsenic, and other elements through a complex network of faults. These fluids were injected into fractures in short, high-pressure bursts, forming “dyke-like” lodes composed of quartz, stibnite, and sulphide minerals. One of the most fascinating aspects of the Costerfield mine is the presence of both gold and antimony within the same vein system. Antimony, commonly found as the mineral stibnite, is now considered a critical mineral due to its importance in global supply chains, including energy storage, flame retardants, and military applications. With most of the world’s antimony supply dominated by China, deposits like Costerfield are becoming increasingly important on a global scale. This video explores how this billion-dollar gold antimony deposit formed, why it is so structurally controlled, and how miners are able to extract such high-grade ore from veins that can be thinner than your arm. We take a closer look at the geology of the Costerfield reef system, the role of hydrothermal fluid flow, and the unique processes that concentrated both gold and critical metals into such a small area. If you’re interested in gold prospecting, mineral exploration, economic geology, or Australian mining, this is one of the most fascinating deposits you’ll come across. From narrow vein gold mining to the global importance of antimony as a critical mineral, the Costerfield mine is a perfect example of how small geological structures can produce massive economic value. Studies Used To Construct This Video: Gold mobilization during cleavage development in sedimentary rocks from the auriferous slate belt of central Victoria, Australia; some important boundary conditions: https://pubs.geoscienceworld.org/segw... Costerfield antimony-gold deposit, southeast Australia: Coupling between brittle deformation and dissolution-precipitation reactions in the Melbourne Zone: https://www.sciencedirect.com/science... Thank you so much for watching! Check out the OzGeology website: https://ozgeology.com If you are in a position to support our channel on Youtube Membership or by joining our Patreon, the link to all of this can be found below: 🎥 If you would like to support this channel, consider joining our Patreon:   / ozgeology   👉 You can also click the "join" button to join our Youtube channel's membership. Every contribution helps to create more videos. YouTube Membership:    / @ozgeologyofficial   🌋 Subscribe to our Youtube Channel: https://www.youtube.com/channel/UCxLr... 💥Link To Our Facebook:   / ozgeology   🌏 About OzGeology The core mission of OzGeology is to make geology exciting, accessible, and inspiring for everyone. Instead of presenting rocks and earth science as dry or overly academic, OzGeology brings stories of the planet to life, revealing how every mountain, mineral, and landscape tells part of Earth’s grand adventure. The goal is to help people see the world differently, to understand the dynamic forces shaping Australia and beyond, and to spark curiosity in the next generation of geologists. Through engaging storytelling, field exploration, and clear explanations, OzGeology turns the study of our planet into a journey of discovery rather than a classroom lecture.