Montana was built on mining, and the state continues to reveal more potential as a world-class copper-mining jurisdiction.
Known as “the Treasure State” because of its vast wealth of mineral reserves, Montana was built on mining, and the industry continues to play in active role in the state’s economy.
Metal mining, according to the Montana Mining Association, accounts for nearly 7,000 direct and indirect jobs, representing US$579 million in labor income and contributing over US$1 billion annually to Montana’s GDP.
Montana’s rich mining history
The first gold discovery in what was known as the Montana territory occurred in 1852 at Gold Creek, near present-day Garrison. Major discoveries of silver, copper and coal would soon follow. By 1862, the region was in the throes of its first gold rush following a big strike at Grasshopper Creek, which two years later would lead to the birth of Bannack, the first territorial capital city. Soon pilgrim prospectors from as far away as Europe were flooding into the gold-mining camps of Western Montana, including Virginia City and Helena. The territory’s growing population and economy (gold production reached into the hundreds of millions) would earn it statehood in 1889 with Helena as the permanent capital.
Over the next decade, copper would dethrone gold as the predominantly mined metal in the Treasure State. Copper mining centered on the prolific Butte mining district, which would grow to become a city with more than 100,000 inhabitants. Butte’s significant silver deposits and enormous copper deposits would earn it the distinction of being “the Richest Hill on Earth.”
By 1896, this “rich hill” was responsible for at least 210 million pound of copper production — more than half of US supply and more than a quarter of the world’s copper supply at that time. By-product gold and silver production would have been worth approximately US$500 million today. Past-producing mines in the region include the Revenue mine, the Broadway gold mine and the Green Campbell mine.
Montana’s geology favorable for copper
Montana has three tectonic provinces with the right geology for copper exploration, known as the Great Falls Tectonic Zone, the Montana Lineament and the Absaroka Volcanic Belt. All the past gold and copper discoveries and operating mines in the state are located in these three tectonic provinces, said Stan Korzeb, economic geologist for the Montana Bureau of Mines and Geology (MBMG), and a research professor at Montana Tech.
“Porphyry copper-gold deposits are known to be centered on intrusions, skarn, carbonate-replacement and sediment-hosted gold deposits in peripheral locations and related to high- and intermediate-sulfidation epithermal deposits,” said Korzeb. “The three tectonic zones are known to have these types of deposits, making them geologically favorable for future copper and gold exploration.”
The Great Falls Tectonic Zone is a northeast-trending structural zone that extends from Southwest Idaho up through Butte in Western Montana to the Canadian border. “A variety of mineral deposits are known to be associated with the magmatic events that occurred along this fault system during the late Cretaceous and early Eocene, including alkaline igneous-related gold, volcanic-hosted epithermal gold veins, porphyry copper and molybdenum and contact metamorphic systems,” said Korzeb, who through his research at the MBMG is currently working on the reexamination of Montana’s historic mining districts for potential exploration targets.
The mineral-rich geology in this region of Montana makes it an attractive hotbed for copper exploration. There are at least two dozen known porphyry deposits in Montana, half of which are copper porphyry. These types of deposits are the world’s most important source of copper and are typically large scale, amenable to low-cost mining with decades-long mine lives. The landmark Butte copper mine is an excellent example of this type of deposit; the Butte mining district reportedly produced 23 billion pounds of copper and three million pounds of gold over the course of a century.
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Policies encourage environmentally responsible mining
“There is great support in Montana for accessing ore bodies, in an environmentally-responsible manner, for the benefit of Montanans,” said Tammy Johnson, executive director of the Montana Mining Association. In a 2016 Montana Chamber of Commerce poll, 73 percent responded that they believe Montana should encourage mining. The poll was conducted by Moore Information and included 800 live interviews among a representative sample of voters in Montana.
Johnson also said, “the Montana Mining Association would like to emphasize that mining, when done correctly and in compliance with stringent State and Federal requirements, is a benefit to our economy. Well-paying jobs that can support a family are in short supply, and the jobs provided by the business of mining are very beneficial to local, regional, and statewide economies.”
Montana’s regulatory regime is structured to ensure that permitted mining projects operate in a socially and environmentally responsible manner before, during and after the development of a mine.
“There is a law in Montana that bans the use of cyanide leaching for open-pit gold mines. This law effectively stopped future open-pit gold mining, and as a result Montana was passed over for exploration projects in the past,” explained Korzeb. “The exception to the law permits the use of cyanide leaching for underground gold-mining operations. Because the future in mining depends on exploration for deep mineral resources mined by underground methods, this change in exploration focus has created future exploration opportunities in Montana.”
Korzeb said these future exploration opportunities will be for deep-seated mineral resources related to historic mining districts that have not been explored for decades. Due to an exception in the cyanide law for underground mines, the cyanide ban will not have an impact on future underground operations.
Mining in Montana today
With sufficient infrastructure in place, Montana’s modern mining industry is alive and well. Large-scale producers currently in operation, including Barrick Gold’s (TSX:ABX,NYSE:ABX) Golden Sunlight gold mine. Montana Resources owns and operates a portion of the Butte system known as the Continental Pit mine — which still has at least another 20 years of mine life.
Today, copper is the second-most-produced mineral in Montana, accounting for a significant percentage of the state’s US$925 million worth of mineral production in 2016; in fact, as reported by the US Geological Survey, Montana is the fifth-largest copper producer in the country.
Montana is a hotbed for exploration as well. “Montana remains a favorable jurisdiction for copper exploration, as witnessed by three projects in various stages of permitting and/or litigation, including the Rock Creek mine project, the Montanore mine project and the Black Butte copper project,” said Johnson.
Broadway Gold Mining (TSXV:BRD) is exploring for copper and gold in Montana’s historic Butte-Anaconda mining region. The Madison project, which lies in the historic Silver Star Mine Camp, includes the past-producing Broadway gold mine — a copper-gold skarn deposit that yielded approximately 144,000 ounces of gold between 1880 and 1950, with historical grades of 9 to 24 g/t gold and 10 to 20 percent copper.
During Phase III drilling, which started in the third quarter of 2017, Broadway identified a copper porphyry system underneath the previously mined skarn zones at Madison. This mineralization exhibits similar characteristics to the latite porphyry hosted at Barrick’s Golden Sunlight mine, located 36 kilometers away. Exploration is ongoing at Madison, and Broadway’s management believes the property has real potential to develop into a large-scale copper and gold porphyry project.
Black Butte, owned by Tintina Resources (TSXV:TAU), is the world’s second-highest-grade development-stage copper project. Located north of White Sulfur Springs, the project hosts the Johnny Lee deposit, which has a copper concentration that is 10 times that of many modern mines — nearly 1 billion pounds of copper in roughly 12 million tonnes of mineralization, according to the company.
“Companies are working with local governments and communities on diversification, attraction and growth of other businesses and industries that can complement mining. Mining has played, and will continue to play, a significant role in Montana’s economy,” said Johnson.