{"version":1,"type":"rich","provider_name":"Libsyn","provider_url":"https:\/\/www.libsyn.com","height":90,"width":600,"title":"Coffee with Samso \u2013 The Discovery of the Prominent Hill IOCG Deposit, Gawler Craton, South Australia - The Discovery that Proved Mineral Exploration for Deposits Under Cover.","description":" Coffee with Samso | Episode 215 | Adelaide Markets | Adelaide | South Australia Guest:  Derek Carter \u2013 Managing Director (later Chair) of Minotaur during the discovery period Tony Belperio (Exploration Lead) \u2013 Exploration Manager Barry Van Der Stelt (Contract Geologist) \u2013 first recognition of copper Peter Reid (Senior Geologist) \u2013 senior geologist involved in the Prominent Hill work Introduction In this Coffee with Samso episode, I went back to Adelaide to sit down with the people who were there when Prominent Hill was found \u2014 the discovery that became one of South Australia\u2019s defining IOCG (Iron Oxide Copper-Gold) stories. This is not a corporate recap. It is a first-hand account of what actually happened in the lead-up to discovery, how the target was chosen, what the drillers and geologists saw in the core shed, and why a single drilling decision could have changed everything. The team shared the backstory from the early tenement holders right through to the Uranus prospect becoming Prominent Hill \u2014 and the reality is simple: discovery is often a chain of decisions, relationships, and technical judgement made under uncertainty. 1) Prominent Hill Was Not a \u201cNew\u201d Area \u2014 It Was a Patiently Reworked Story A key point in the conversation was that the Mount Woods ground had history well before Minotaur. The tenements were originally held by Metals X, who worked the region from the late 1980s onward, focusing on magnetic features and drilling at least one early target. Later, Burmine Limited entered the picture, and then Normandy\/Poseidon ran a helicopter-based gravity survey across the area. Burmine Limited (ASX code: BUR1) was an Australian-listed gold and minerals exploration and mining company active in the late 1980s and early-to-mid 1990s. It was primarily focused on Western Australian gold projects, notably operating the Copperhead mine near Bullfinch. This matters because it shows the reality of exploration cycles: ground can be worked, tested, and even partly understood \u2014 but still not properly unlocked until the right targeting logic arrives. 2) The Technical Pivot: Magnetics Were Useful, But Gravity Was the Key The story turned when the targeting mindset shifted. Earlier programs were chasing magnetic features \u2014 and while they were hitting copper-bearing magnetite breccias, there was a ceiling to the grades being intersected. The breakthrough came when the team could simultaneously interpret magnetics and gravity, and start looking at where these anomalies were offset from each other. The concept was simple but powerful: Magnetic anomaly = something magnetic Gravity anomaly = something dense Offset between the two can be the clue to a different part of the IOCG alteration system This is where the conversation became very \u201creal exploration\u201d: data doesn\u2019t tell you it\u2019s mineralised. It tells you where you should be brave enough to test. 3) 3D Modelling Was a \u201cGame Changer\u201d \u2014 And It Was New Back Then One of the most important takeaways was how early this team was in adopting 3D inversion modelling. Today we treat 3D models as routine. Back then, it was cutting-edge. The team explained how the modelling allowed them to rank targets properly, separate those already drilled from those not tested, and better understand the geometry of gravity and magnetic responses. In Samso terms: this was one of those moments where technology didn\u2019t replace geology \u2014 it amplified it. 4) \u201cUranus 1\u201d \u2014 The Discovery Hole That Almost Looked Like Nothing The drill hole that changed everything was Uranus 1. Barry Van Der Stelt described the core and is the kind of detail that explorers remember for life: The core was so hematite-rich it was hard to even see textures. The team was washing core just to interpret it. The operation was low-budget \u2014 even the core cutting was done on a basic brick saw setup. Then came the moment: blue specks appearing after the core had sat for a couple of days. That blue tarnish was the first real visual signal of copper \u2014 and it triggered the call that brought the team running. This was also a reminder that Prominent Hill echoed the Olympic Dam story: sometimes the copper is not obvious until it\u2019s tested, altered, or routinely assayed. 5) The Numbers Were Bigger Than Anyone Expected The team admitted they initially thought they might have something like \u201c30 metres of ~1% copper.\u201d Then assays came back with results that were materially stronger, including: a high-grade copper interval around 4% copper over ~30m, and broader zones around ~1% copper that they simply could not visually recognise in hematite breccia. Later, deeper drilling confirmed additional IOCG-style signatures, including: copper-gold mineralisation and uranium increasing at depth, reinforcing the Olympic Dam-style system interpretation. 6) The Sliding Doors Moment: Drilling the Flank, Not the Core This is one of the most valuable exploration lessons in the episode. After the discovery hole, infill gravity shifted the interpreted peak of the anomaly by several hundred metres. The team realised they had not drilled the very centre. The irony is that drilling into the \u201cpeak gravity\u201d later hit barren, intensely altered hematite-silica core, which is now recognised as central IOCG alteration. The team openly discussed the risk: in 2001, if they had drilled the core first and hit barren alteration, they might have walked away. That is a brutal truth about exploration: a discovery can be decided by where you hit a system first. 7) The Business Reality: Minotaur Had Only 19% \u2014 But It Was Enough One of the most interesting parts of the conversation was the structure. Minotaur\u2019s maximum share of the project was 19%, while the major partner (BHP\/Billiton through the merger timeline) held the majority position. Minotaur\u2019s \u201ccost\u201d for that 19% wasn\u2019t cash \u2014 it was local geological knowledge and management. The team framed it with a simple idea that still applies today: Better to own a piece of something real than 100% of something you can\u2019t fund. This is a proper junior-to-major alliance lesson, and it explains how big discoveries are sometimes possible in down cycles. 8) Capital Cycles Still Matter The group reminded us that this happened during a period when market attention was elsewhere \u2014 the dotcom era, when exploration was not \u201cin fashion.\u201d And yet, the discovery still drove a dramatic market response: strong share price movement, heavily oversubscribed shareholder participation, major legal\/accounting work managing scale and compliance. The point wasn\u2019t hype. It was showing how quickly markets can change when geology delivers. What This Episode Really Shows This Coffee with Samso episode is a reminder that discovery requires: Local knowledge (not just imported models) Funding and deal-making (alliances matter) Technical courage (you still have to drill the target) Open-minded thinking (don\u2019t get trapped by one model) A tolerance for failure (because near-misses are common) Prominent Hill wasn\u2019t found because everything was obvious. It was found because the team kept moving forward, making decisions with imperfect data, and backing their judgement. Samso Concluding Comments For me, episodes like this are part of documenting the real value chain of discovery. A lot of people talk about the \u201cnext Olympic Dam\u201d like it\u2019s a marketing phrase. This conversation shows what that actually looks like in practice: long lead times, multiple parties, tight budgets, imperfect data, and a team that had the discipline to keep testing. If you want to understand how IOCG discoveries really happen \u2014 this is one to watch. ","author_name":"Coffee with Samso","author_url":"http:\/\/samso.libsyn.com\/www.samso.com.au","html":"