New Finds in Old Ground: How Modern Exploration is Revisiting Historical Deposits

Pricing rewrites economics

Commodities prices are not the sole deciding factor for either revisiting or leaving behind a historic deposit, but they play a role in the process. Research suggests that the traditional buffer between copper price assumptions and actual London Metal Exchange prices has virtually disappeared. The finding is that project developers are adopting long-term prices that mirror or occasionally exceed current market forecasts.

In early 2026, copper prices rallied to record territory, above US$13,000 per tonne, pushing companies to reevaluate mines that have sat idle for years. One example would be the scheduled reopening of Sibanye-Stillwater's (NYSE:SBSW) Mount Lyell on Tasmania’s west coast. The century-old copper-gold mine had been on care and maintenance since 2014 before the company approved its restart in 2026. General manager Clint Mayes called rising copper prices "a nice sweetener” to the project’s new life, adding that the call ultimately came down to long-term demand forecasts.

Meanwhile, JPMorgan Chase (NYSE:JPM) said that geopolitical conflict in the Middle East and the closure of the Strait of Hormuz drove up copper prices earlier this year. The firm has also flagged copper policy uncertainty in the US, where a pending Section 232 review could bring new import tariffs.

Like most numbers in a project, prices matter. A deposit that wasn't worth the cost of more drilling, metallurgical testing or new infrastructure a decade ago can look very different when the metal it holds is trading near record highs. It even proves to be more beneficial when most factors like historical drill data, permits and access roads are already in place.

From oxide to sulfide processing

Beyond pricing, there's also processing. Many historical exploration projects pursued oxide mineralization, since it can offer a simpler processing path with a cheaper, faster route to production. The process is simple: acid is poured over crushed ore to dissolve copper, then the copper is pulled from that solution and turned into finished copper cathode. It's a straightforward, low-cost setup that can produce copper directly on site. However, it is limited to only oxide deposits, and cannot easily recover any by-product metals that may be present, such as gold and silver.

Processing of sulfide mineralization works differently. The ore is crushed and ground, then treated to produce a concentrate that's shipped off to a smelter, typically through a method called froth flotation. It costs more to build and run, but it can effectively process sulfide ores, which can often be much more significant in size than a smaller oxide deposit. Sulfide processing circuits can typically also recover gold, silver and numerous other by-product metals.

This can be one of the reasons why many historical deposits still have untested areas today. If the plan was to use an oxide processing circuit, once a drill hole hit sulfide material, it would fall outside what the mine was set up to handle. This could lead to plenty of untested sulfide mineralization sitting just below or beside known oxide zones, with the opportunity to unlock significant value in these historical deposits with modern exploration tools, updated geological models, and changes in planned processing techniques.

Cascadia Minerals’ Carmacks project

Cascadia Minerals is revitalizing one of these historically underappreciated properties. Located 35 kilometers from the past-producing Minto mine is its 100 percent owned Carmacks project, with a resource defined by roughly 44,000 meters of historical drilling. The project covers approximately 177 square kilometers in the Minto Copper Belt, part of the same Stikine Terrane that hosts major copper-gold porphyry deposits in BC like Red Chris, Schaft Creek and KSM.

With a measured and indicated resource of 36.3 million tonnes grading 0.81 percent copper and 0.26 grams per tonne gold (or 1.07 percent copper equivalent), Carmacks comes with a 2023 preliminary economic assessment showing a post-tax net present value of roughly C$230 million and a 29 percent internal rate of return.

Previous activity was focused primarily on oxide copper mineralization, and historical drill holes were often terminated once they hit sulfide material. Cascadia Minerals has recently completed what it describes as the first major drill program at Carmacks in roughly two decades, an 18,000 meter campaign aimed at testing that sulfide potential directly for the first time.

The drill program itself marks a significant milestone not only for the company, but demonstrates the potential that can be present with a modern re-look at a property. Revitalizing the Carmacks project serves as proof that historical projects can have a lot more to offer.

In addition to its work at Carmacks, Cascadia has also entered into a strategic alliance with Agnico Eagle Mines (TSX:AEM,NYSE:AEM) to focus on gold and copper exploration in the Yukon’s Stikine Terrane, with up to C$5 million in exploration funded by Agnico Eagle in 2026.

Investor takeaway

There are numerous deposits that have been known about for years, if not decades, where untapped potential can be unlocked with new tools and methods. Today’s mining environment can help advance many of these projects that have languished in the past.

As copper prices continue to stay at record highs, projects with existing data and infrastructure are seeing growing attention. Investors may turn to the likes of Cascadia Minerals’ Carmacks project, which demonstrates how digging deeper can help companies find what could be the next best thing. Discoveries with significant value may already be known; they have just been waiting for the right processes, pricing and approach to bring them to fruition.

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