News

Duluth News Tribune
March 23, 2010

Mark Severson is seen in his early years of drill core analysis at the Department of Natural Resources Drill Core Library in Hibbing. (Submitted photo) Mark Severson has been studying northern Minnesota rock for 23 years, one foot at a time, more than 1 million times.

Severson, a geologist with the University of Minnesota Duluth's Natural Resources Research Institute, looks at core samples of rock drilled from across Northeastern Minnesota's so-called Duluth Complex - the billion-year-old rock formation now known to hold billions of dollars worth of copper, nickel, platinum and other valuable metals.

"His work is really the impetus for all the activity we are seeing up there now. It's the basis for the all the exploration,'' said Steve Hauck, NRRI deputy director of the Economic Geology Group.

On March 11, about 10 miles west of Hoyt Lakes, Severson eyeballed his one-millionth foot of core sample rock, all the while keeping track of the trace elements of minerals he saw and noting where the samples came from.

That's 190 miles of 2-inch-diameter cylinders of rock that would stretch from Duluth to Faribault.

Experts say Severson has plotted the roadmap of sorts showing where the richest and most accessible minerals are located, and it's his work that prospectors and mining companies use when they decide where to stake their claim and look for a place to dig a mine.

Rich Patelke, chief geologist for PolyMet Mining Co., said the company doesn't always know what they'll find when they drill test holes at their proposed mine site. But it's usually pretty close to what Severson guesses beforehand.

"Imagine walking from Hoyt Lakes to Minneapolis and being able to describe, after the trip, the white line along the highway the entire way,'' Patelke said. "Mark's got an incredible skill, an eye and a visual memory that can't be beat. He remembers what he saw years ago.''

Many of the core samples Severson has examined were drilled in the 1960s but cast aside as being not valuable enough to warrant further exploration, let alone mining. Other samples, such as those Severson was studying Monday at PolyMet's proposed operations, were just recently drilled as companies try to pinpoint the richest deposits and map their mine sites.

Patelke said Severson was the first to understand the various layering patterns of valuable minerals and how they correlate "from drill hole to drill hole to drill hole.''

"The earlier work just wasn't recognizing the geological continuity between holes,'' Patelke said.

Severson said he wasn't sure if the large amounts of lower-grade metals he was finding in core samples would ever be worth the effort to mine. Now, a half-dozen companies are planning copper-nickel mines, based in large part on what he found.

"I always wondered if this would happen, if they could develop what we were finding down there,'' Severson said Monday. "What's happened is that the technology to pull the ore out of the rock cleanly and economically has finally caught up. ... It took all these years for that to happen.''

Since 1987 Severson has logged thousands of hours studying the slender cylinders of rock. The samples, broken into manageable lengths, originally ranged from 50 to more than 5,000 feet long. Most were stored at the state Department of Natural Resources storage facility in Hibbing. But Severson also has studied core samples outdoors at the drilling sites and inside high-tech labs.

Usually, though, his work has been dusty and lonely, with more mice than people as company.

"I was looking in one warehouse outside when it was 20 below zero and all I had for light and heat was my Coleman lantern,'' Severson said.

Severson is now confident that mining companies will be able to develop environmentally safe mines to extract copper, nickel and other metals in Minnesota. That's at least in part because his work has helped them avoid rock with high sulfide levels that might spur sulfuric acid runoff into local waterways.

"If they clear the environmental hurdles - and they should - I think they [planned copper mines] will be developed,'' he said. "It's looking good.''