The notion of a gold rush in northern Minnesota has taken a big hit with the exit of one of the world’s largest gold mining companies.

AngloGold Ashanti had scooped up 271 state precious-metal mining leases in recent years, encompassing 105,900 acres. But the company terminated them at the end of last year, quietly ending a significant exploration project here to focus on a more promising venture in Nevada.

“It’s definitely a blow in some respects for exploration in Minnesota,” said Dean Peterson, program manager for the economic geology group at the Natural Resources Research Institute at the University of Minnesota Duluth.

South Africa-based AngloGold Ashanti in recent years has held more state precious metals leases than any other company, including several copper-nickel joint ventures.

With AngloGold’s departure, the total number of active state leases has fallen from 461 last October to 191 at the beginning of this month — near a 15-year low, according to data from the Minnesota Department of Natural Resources (DNR).

“They were by far our largest leaseholder,” said Heather Arends, the DNR’s minerals potential manager.

AngloGold’s leases were concentrated in northeastern Itasca, western St. Louis and southeastern Koochiching counties.

Leasing land is an early step in the long process of trying to development a mine. “To go from leasing to drilling to starting a mine — they are all orders of magnitude,” Peterson said.

Indeed, 82% of all state nonferrous leases — those that are not for iron ore — between 1966 and 2018 were terminated within five years, according to the DNR, and nearly 98% of those involved no exploration drilling.

AngloGold had drilled 154 holes through the winter of 2019. But in December, the company terminated its leases rather than holding them and continuing to make payments.

“We spent a few years there doing some basic exploration work and decided we would go in a different direction,” said Sabrina Brockman, AngloGold’s senior vice president for investor relations and group communications.

AngloGold, with a stock market capitalization of $11 billion, has large mines in Africa, Australia and South America. Its U.S. exploration efforts in recent years have focused on Nevada and Minnesota.

With AngloGold gone, Vermillion Gold appears to be the only mining outfit focused on gold exploration in Minnesota, at least on state lands. The Minnesota company has 14 state leases, according to DNR data.

Precious metals mining has been a hot topic in Minnesota in recent years, particularly copper-nickel mines proposed by PolyMet Mining Corp. and Antofagasta’s Twin Metals.

PolyMet, owned by Swiss mining giant Glencore, last year had been moving closer to breaking ground on a $1 billion, fully permitted mine in northeast Minnesota. But environmental groups successfully challenged its state permits. The fight is now before the Minnesota Supreme Court.

Prospective gold mines in Minnesota are much further out than copper-nickel mines, but the issues are similar.

Proponents say such hard-rock mines would bring well-paying jobs to economically strapped northeastern Minnesota. Opponents say they are a dire pollution threat to Minnesota’s lakes and streams, including — for the Twin Metals project — the Boundary Waters.

Minnesota’s mine permitting process wasn’t a factor in AngloGold’s departure from Minnesota, Brockman said. “We do business in a lot of tricky places with a lot of stakeholder groups.”

Prospectors have been looking for gold in northern Minnesota since the 1860s with little to show outside of a successful strike at Rainy Lake in the late 1890s.

Renewed interest in Minnesota gold surged in the 1980s, with active state precious metals leases hitting an all-time high of 783 in 1983.

That was driven by relatively high gold prices coupled with commercial gold strikes in Ontario north of eastern Lake Superior. Today, there are five gold mines in that area, and three more further west, including one about 40 miles northwest of International Falls.

The geology of northern Ontario and a swath of northern Minnesota are similar, all belonging to what’s called the Abitibi-Wawa greenstone belt. On this terrain, miners face a similar challenge: Economically extracting gold from ancient bedrock buried beneath layers of glacial till — i.e., sediment deposited by moving glaciers.

The glacial till layer in Minnesota on average is deeper than that in much of Ontario, Peterson said. “It impedes exploration.”

By Minnesota law, exploration companies must turn over data — including drilling core samples — and AngloGold should provide geologists with a trove of new information. The DNR has released some AngloGold data, but the bulk of it is likely to be published by the end of the year.

An important factor for further gold exploration in Minnesota is the trajectory of gold prices. Prices have been relatively high for the past decade, but they’ve particularly surged this year due to the economic uncertainty wrought by COVID-19. Gold is now trading around $1,900 an ounce, down from a peak of over $2,000 in August, the highest price since gold crossed the inflation-adjusted mark of $2,200 in 1980.

“It’s a good time to explore because prices are high,” Peterson said.