Western USA Exploration
In search of a new manifest destiny
Apart from numerous Native American tribes like the Yaqui, Hopi, Ute and Washoe, mineral explorers were some of the first to settle the Western US. As the country expanded, the West emerged as a vast, uncharted frontier, offering a new horizon for those daring enough to venture into its rugged landscapes. The region became a symbol of opportunity—a place where the bold could carve out their fortunes from the untapped riches buried beneath the earth. The allure of the West was about the prospect of discovering gold, silver and other precious metals that lay hidden in the mountains and valleys, waiting to be unearthed by those with the grit and determination to find them.
In 1890, the Census Bureau declared the Western frontier closed. 135 years later, the Western US has become a new symbol of opportunity for explorers: an untapped, mineral rich region with the ability to supply the ever-demanding globe.
The Western US’s complex tectonic history, marked by subduction zones, volcanic activity, and crustal stretching, created the perfect conditions for the formation of mineral deposits. Key tectonic events shaped today's productive mining regions, with each era playing a role in concentrating metals in economically viable deposits.
Precious lands, precious metals
The western United States' prolific gold and silver deposits owe their origins to a rich tectonic history involving subduction, mountain building, and crustal extension. Starting in the Paleozoic, ancient Precambrian crustal blocks were accreted along North America's western margin, creating the foundation for mineral-rich volcanic arcs. Precambrian- aged rock are being discovered today at Silver One’s Candelaria project in Nevada. These rocks contain high-grade silver, said Greg Crow, the firm’s president and CEO: “Our property has seen historical high-grade polymetallic veins, and we are currently discovering new high-grade silver vein fragments through metal detecting, with the largest fragment weighing 417 pounds and estimated to contain about 70% pure silver.”
In the Mesozoic, subduction of the Farallon Plate generated major orogenies, including the Nevadan and Sevier, which drove magmatic intrusions that injected gold-bearing fluids into fractures across Nevada, Idaho, and Utah. As these intrusions cooled, they emplaced veins of gold and silver within faults and fractures, leading to deposits like the Comstock Lode in Nevada. In 1859, the Comstock was the first site of silver discovered in the U.S. The legacy and reserves, continue to this day. “We have a fully permitted infrastructure and 12 square miles of contiguous mineral properties on the historic Comstock. Our Dayton Consolidated mine holds 250,000 to 300,000 oz of gold and 3-4 million oz of silver,” said Corrado De Gasperis, executive chairman and CEO at Comstock Inc.
The Comstock Lode in Nevada was part of the wave of silver mining targeting carbonate replacement deposits (CRDs) across the West. These deposits form when mineral-rich hydrothermal fluids replace carbonate rocks with metal-rich sulfide minerals, creating zones of silver, lead and zinc. Their high grades make them attractive to this day, said Kit Marrs, co-founder, CEO and president of Western Alaska Minerals, who discovered a CRD containing 75 million oz of high-grade silver equivalent: “This high grade results in significant profit margins compared to low-grade copper deposits, which require extensive capital to develop. CRDs typically have a lower environmental footprint and involve lower capital costs, making them more appealing now that exploration priorities have shifted.”
Though many of these deposits were mined a century ago, Barksdale Resources, also encountered CRD style mineralization in the Patagonia district of Arizona, adjacent to South32’s Hermosa’s CRD. “The first hole into the CRD area encountered 13 mineralized zones, though they were thinner than historic intercepts. Key highlights included a 1-meter intercept with 8% copper and polymetallic sulfide masses with 15-20% lead-zinc and up to 100 g/t silver,” said Rick Trotman, president and CEO of Barksdale Resources.
During the Miocene, low-sulfidation epithermal gold and silver deposits formed due to extensional tectonics. Notable examples are found in the Great Basin region, including areas like Nevada’s Carlin and Cortez Trends, creating the largest and richest gold regions globally. The hunt continues in the area, with NV Gold Corp’s SW Pipe project covering 85 claims. “We have with excellent access and are situated in elephant country. The geochemical signature we observed, especially at the intersection of two major faults, is encouraging. The small surface gold deposit might be a surface indicator of a larger, deeper system,” said John Watson, the president and CEO.
The meeting of the precious and the industrial
Before the Miocene, the Laramide orogeny moved the center of tectonic activity inland. Porphyry copper-gold systems emerged during this time as deeper magmatic intrusions were emplaced, forming extensive hydrothermal systems that introduced copper and gold into the crust. Most of Arizona’s major porphyry copper systems are linked to the Laramide event, and the next one likely will be too. “Porphyry copper deposits are characterized by specific styles of alteration, mineralization, geophysical signatures and occur in Laramide age intrusives,” said Elmer Stewart, president and CEO of Copper Fox Metals, whose three projects are in fertile Laramide age intrusives.
Porphyry copper-gold deposits are found in the Northern Cordillera, which extends through the Rockies and up to the Alaska Range. They form from hydrothermal fluids related to the cooling of magma deep within the Earth’s crust. These fluids moved through fractures in the rock, depositing copper and other valuable metals like molybdenum and gold as they cooled. The result is vast, low-grade but highly concentrated deposits of copper, such as those found in Arizona’s Morenci and Bingham Canyon mines. These deposits are so large and rich in copper that they have sustained mining operations for over a century, making them some of the most important sources of copper in the world. “Porphyry deposits are large, making them easier to locate than narrow high-grade veins. Their grade characteristics lend themselves to bulk tonnage, lower-grade mining operations with higher throughput. They are crucial for meeting the global demand for gold and copper,” explained Tim Smith, CEO and president of U.S. GoldMining.
Porphyry deposits, while typically characterized by evenly distributed mineralization, can exhibit unique geological variations that influence their economic viability. For example, the CuMo deposit in Idaho, a hard rock copper porphyry, presents a distinctive stockwork system. “The nature of our orebody provides significant opportunities to lower CapEx. Unlike typical porphyrys where mineralization is evenly distributed throughout the ore body, our deposit has thin, finger-width veins containing the bulk of the copper, molybdenum, rhenium, and tungsten minerals,” said Andrew Brodkey, chief operating officer at Idaho Copper.
“Historically thousands of junior exploration companies would comb the Earth, one would make a viable discovery, and would be acquired by a major. Now, juniors are undercapitalized and miners are depleting their reserves. Technology is the only solution.”
Corrado De Gasperis, Executive Chairman and CEO, Comstock Inc.
A key aspect of porphyry systems is the presence of breccias— rock formations composed of broken fragments cemented together by a fine-grained matrix. Breccias, formed by intense hydrothermal activity, serve as both hosts and conduits for mineralizing fluids. As these fluids traveled through the fractured rock, they deposited copper and other metals, creating zones of higher-grade mineralization within the broader porphyry system. At Faraday’s Copper Creek, newly discovered at surface breccia are enhancing the economics of the deposit, said Paul Harbidge, president and CEO: “The first new target we drilled, Area 51, resulted in the discovery of a cluster of breccias exposed at surface with strong copper mineralization. Assay results include: 1.29% copper over 11.36 meters within 45.75 meters at 0.48% copper.”
New copper discoveries are sparse, amid a global shift away from early-stage exploration. While copper exploration budgets grew 12% during 2023, most of this funding was directed toward brownfield exploration, according to S&P Global. In S&P Global’s analysis of 239 copper deposits discovered between 1990 and 2023, the US and Canada combined accounted for only 10% of discovered copper.
Today’s porphyry hunt is assisted by tools not available to the miners of the old west, revealed Eric Saderholm, managing director of exploration and co-founder of American Pacific Mining Corp.: “Radiometric data detects potassium, which is important for copper porphyry exploration. It highlighted key features and advanced our understanding of the project, allowing us to focus our efforts more effectively.”
Barrick Gold is on the hunt for porphyry elephants, in the firm’s move to increase copper exposure. "Copper is as strategic as gold is precious. As you grow as a gold miner, you have to embrace copper. To keep critical mass, you've got to go to the porphyries—porphyry gold deposits—and with those porphyries come copper as well," Mark Bristow, their CEO told Kitco in an interview.
This is evident in Barrick’s strategic US$23.5 million investment to acquire a 12.5% stake in Hercules Metals Corp. in Idaho, following a geophysical survey that revealed a deep anomaly, which was later confirmed as a major porphyry copper system. “Barrick has a strong interest in this district due to its potential as a new porphyry copper discovery. Porphyry copper often occurs in clusters, so one discovery could lead to others. Barrick sees this potential and is actively supporting us with both capital and technical guidance,” confirmed Chris Paul, CEO of Hercules.
“By leveraging AI to interpret subtle geological signals and predict subsurface mineralization patterns, mining companies can unlock new exploration opportunities in resource-rich yet underexplored regions.”
Lorraine Godwin, Vice President Commercial, VerAI
Manifest destiny’s legacy
In 1872, the United States government formalized the opportunity to exploit the US’s geological riches through the mining law, a piece of legislation that opened the doors to the mineral resources on public lands. Anyone who could find valuable minerals could stake a claim. The mining law reflected the broader spirit of the time, a period when the nation was focused on growth, expansion, and the harnessing of its natural resources. “The law is still in effect and is old and complicated,” emphasized Chris Summers, CFO of Burgex Mining Consultants.
Claims are also no longer free, continued Summers: “The basic maintenance fee has gone up from US$165 to US$200 per claim, which is significant when multiplied by thousands of claims. We are already seeing companies not renewing claims due to the fee increase. While the BLM is mandated to review fees every five years, the magnitude of this year's increase is significant. It is disheartening because we need this investment for the US to achieve its goals, particularly for the green energy transition.”
Investment strategies, however, may shift as high commodity prices create new opportunities. Mike Sieb, president of Getchell Gold explained: “When investors realize profits from the established producers, they will seek undervalued opportunities in which to reallocate their gains.”
To attract these investors, Getchell is preparing a PEA. “This will serve as a resource for investors, demonstrating the foundational value and upside potential that will position us for future M&A activities usually developed in the wake of a revitalized gold market,” Sieb continued.
Mergers have been purposefully, explained Darrell Tweidt, client services manager at Premier Drilling Co:“The industry is experiencing consolidation, with smaller companies merging to share resources. Many investors are diverting funds to newer markets like AI and cryptocurrencies instead of mining.”
Risk is being diverted to these newer markets at a time when mining needs it most. On top of that, M&A cannot be relied on to mobilize change. “M&A in the sector could bring capital, but true momentum requires more market risk appetite. Investors should look for companies actively advancing projects. Few companies with a US$30 million market cap are investing US$20 million in exploration,” said Warwick Smith, CEO of American Pacific Mining.
This new chapter in exploration history is not just about conquering the land, but about responsibly harnessing its resources to build a more sustainable and self-reliant future for the United States. The stakes are high, but so too is the potential for a new kind of prosperity—one that respects both the land and the legacy of those who first ventured westward.
Article header image by Craig Zerbe at Adobe Stock