Could Utah’s ‘zombie mine’ have another life?

There are few exploration stories that begin with a mine so rich it helped create a town, collapse spectacularly, then keep coming back to life for decades. The Horn Silver Mine in Utah’s San Francisco Mining District is one of them.

Horn Silver has already had two lives. Diablo Resources is now testing whether it could have a third.

Life One: The mine that built Frisco

Discovered in 1875 by prospectors James Ryan and Samuel Hawkes, the mine quickly became one of the most important silver operations in the United States. Over its long production history, the Horn Silver Mine produced around 17 million ounces of silver at an average grade of about 604 grams per tonne, alongside roughly 25,000 to 30,000 ounces of gold, , together with significant lead, copper and zinc

All of that came from a remarkably small footprint: a single mining claim covering about 20 acres, within a deposit roughly 200m long and over 300m deep.

For the frontier community that grew around it, the mine was more than a source of ore. It was the economic engine.

The town of Frisco developed as the commercial centre of the surrounding mining district, with the arrival of the Utah Southern Railroad further connecting the remote operation to markets and processing infrastructure. Historical accounts record a rapidly expanding population, with Frisco becoming a substantial mining camp during the Horn Silver boom.

The scale of the economic activity is perhaps best illustrated by the money flowing through the operation. Contemporary records indicate that Horn Silver’s spending on wages, supplies and freight exceeded $1 million a year in the mid 1880s, while its workforce was still being paid around $30,000 a month.

The mine was therefore supporting far more than miners underground. Its demand for transport, smelting, supplies and other services helped sustain an entire mining economy.

For a time, Horn Silver looked almost unstoppable. But the first life of the mine ended as dramatically as it had begun.

Life Two: The mine that refused to stay dead

Then, in February 1885, the story took a dramatic turn. The upper workings of the mine suffered a catastrophic cave in, with the collapse reportedly violent enough to shatter windows in Milford, about 15 miles away. The mine was temporarily crippled and the associated smelting operation was shut down.  But the Horn Silver refused to stay dead. A new shaft was sunk deeper and mining resumed in 1886. The operation continued for decades, despite periods of inactivity and changing economics. It was eventually closed for economic reasons in 1919, rehabilitated under a new lease in the late 1920s and continued producing intermittently until 1952.

That remarkable ability to survive repeated setbacks is what makes the Horn Silver something of a historical “zombie mine”. It wasn’t simply a mine that closed once and disappeared. It was an operation that repeatedly found a way to come back.

Life Three: Can modern exploration give Horn Silver another life?

For Diablo Resources, the significance of that history is not simply nostalgic. The company is now combining the clues left by more than a century of mining with modern exploration techniques to investigate what may have been missed.

The difference today is the technology available to explorers. Historic miners were largely limited to what they could see, sample and follow underground, whereas modern exploration can combine historical mine plans and geological records with mapping, geochemistry, geophysics and structural interpretation to build a much broader picture of a mineral system.

That creates a particularly interesting question at Horn Silver: how much of the system may have been beyond the reach of the technology available to earlier generations of miners?

The company has now consolidated the broader Horn Silver Project across 202 patented and unpatented claims covering about 13.2 square kilometres, including the ground surrounding the historic mine. That is important because patented ground provides a different tenure position to the unpatented claims that dominate much of the surrounding exploration landscape, giving Diablo greater control over the core historic mine area and allowing exploration to be planned across the broader package

Beyond the historic mine

And the opportunity may extend well beyond the old workings.

While the original Horn Silver operation was built around exceptionally high grade silver-lead mineralisation, Diablo’s modern exploration model is looking at a much broader polymetallic system involving silver, gold, copper and antimony, alongside the historic lead and zinc endowment.

Recent reconnaissance sampling has already provided some promising clues across the broader project. At Buckhorn, a rock sample returned 4,190g/t silver alongside 1.40g/t gold and 2.41% copper. Other prospects, including Washington, Accrington and Michigan, have also returned high-grade silver, gold and copper results, broadening the exploration story beyond the historic mine itself.

Those are grab samples that provide a compelling reason to test whether the mineralisation seen at surface continues beneath cover or along strike.

From history to the drill bit

That is now the next chapter. Diablo is integrating the historical mine plans, geological records and modern sampling results to rank targets across the project. Priority areas include extensions of the historic Horn Silver workings, Horn South, the Gossan target, Buckhorn, Imperial, Washington and Accrington, all  polymetallic targets which the Company views as highly prospective..

The company is preparing a maiden drilling program for Horn Silver, with mapping, sampling, structural interpretation, permitting and contractor planning underway.

More than 70 years after the mine last produced commercially, Horn Silver’s significance has already been proven.

Its first life helped build a town. Its second survived collapse, closure and changing economics.

Now, Diablo is testing whether the mineral system that created one of Utah’s great mining booms still has another life left in it and support a third.

The company isn’t trying to recreate the Horn Silver of the 1880s. It is asking whether modern exploration can find what historical mining could not.

For a “zombie mine” that has already come back to life more than once, that may be the most interesting question of all.

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