HIBBING — For five weeks in January and February a small but dedicated staff of Minnesota Department of Natural Resources employees spent 12 hours a day, seven days a week, scanning about 16,000 feet of drill core in a high-tech mobile lab located out of sight, but in the heart of Hibbing.
The work was part of a DNR Corescan Pilot Study funded by the DNR’s Minerals Management Account and the Department of Iron Range Resources and Rehabilitation, the results of which may shed some light on both how Minnesota’s mineral deposits formed and where undiscovered deposits may be located.
That, according to project leader and DNR Economic Geologist Don Elsenheimer, could bring new mineral exploration companies to Minnesota.
“Companies whose exploration programs would create new jobs and add millions of dollars of economic activity to the regional economy,” he said. “The data from this project will help the DNR manage public lands. The better we understand the state’s mineral potential, the better we can manage and generate revenue on school trust lands.”
According to the DNR, Corescan is an integrated method of mineral and texture analysis that collects and interprets the invisible electromagnetic spectrum (hyper-spectral) image data.
It’s most commonly used on bedrock drill core and most often in support of mineral exploration programs.
Corescan is also the name of the Australian company that developed the technique and offers corescan analyses from both fixed and mobile labs to clients across the globe.
The company’s mobile labs are built in Perth, Australia inside 20-foot-long transport containers that can be moved from one project location to the next via truck, rail and/or cargo ship.
One such lab was set up inside one the DNR’s three Drill Core Library warehouses in Hibbing for much of January and February.
Elsenheimer said Corescan’s mobile lab arrived in Hibbing on a flat-bed truck just after the new year.
“Corescan maps out the minerals within a rock core in far more detail than what a geologist could see with just a hand lens,” Elsenheimer said. “It is also a non-destructive technique that, in contrast to traditional assays, doesn’t force you to cut and crush portions of valuable drill core.”
The Drill Core Library, which is the state’s only such facility and has been in Hibbing since 1972, includes three warehouses filled with just under 4 million lineal feet of drill core samples
The Corescan technology uses advanced imaging, scanning drill core samples row by row, and collecting data that's invisible to the human eye. The results will show how the minerals formed, not just which ones are in there.
“We scanned about 16,000 feet of drill core over a five-week period. The mobile lab scanned 10 feet of core every 15 minutes, so we needed to work 12-hour days, seven days a week to hit that production target,” Elsenheimer said. “Although we did get some time off to watch the Super Bowl.”
In addition to the Corescan technician that worked inside the mobile lab, the DNR always had at least one or two of its geologists on hand to prep and process the core.
“It was a real team effort that drew staff from both the Hibbing and St. Paul offices. I really appreciated the help of colleagues who were willing to work long hours and get their hands dirty for this project, he said.
Mining aides in the Hibbing office also pulled more than 1,500 2-foot long boxes of core off of the library shelves for the project and will put each of those 50-pound boxes back on the shelf now that the scanning part of the project is over.
“These guys also came in on the weekends to help keep the production going, sometimes even in between their kids’ hockey games,” Elsenheimer said. “We couldn’t have done this project without them.”
The core was selected by DNR geologists from the DCL’s archived collection of drill core from more than 9,000 locations within the state.
The corescan method creates a digital record of the drill core’s geology and mineralogy that is archived on (and accessible from) the “cloud.”
This provides a kind of digital insurance policy in case there was a catastrophic loss at the DNR Drill Core Library, the same way that people digitally scan their old print photos and upload them to the internet in case they suffered a loss from flood or fire.
According to the DNR, the mobile lab that was used in the Hibbing DCL was previously in Grand Forks, North Dakota, scanning drill core from the Williston Basin petroleum fields. Before that, this specific mobile lab was based in Mexico.
One of the goals of the DNR pilot study was to confirm its effectiveness for the types of bedrock and mineral deposits that are found in Minnesota.
“This corescan technology has been used as a production tool in some of Australia’s active iron mines. We scanned a fair bit of Minnesota iron formation for this project, and we’re eager to see how Corescan’s benefits Down Under will translate up here on the Mesabi Range,” he said. “Most of the core that we’ve scanned was originally drilled by exploration companies who were looking for deposits of gold, copper, titanium and other valuable minerals. We also scanned Mesabi Range core that was drilled by the Minnesota Geological Survey and funded by Iron Range Resources back in the 1960’s.”
Pilot study drill core was selected to capitalize on the strengths of the technique and collect analyzed data that supports the State’s policy on mineral diversification and mineral exploration (particularly on state-managed mineral rights and within the IRRR’s service area).
DNR geologists also selected drill core based on its ability to support sound scientific research, and/or the evaluation of the technique as a potential production tool for Minnesota’s active taconite mining operations.
Core from roughly thirty-five locations within Northern and Central Minnesota. Those cores are linked to a handful of projects that focus on distinct geological terranes and/or mineral deposits.
The list of mini-projects include:
• The Biwabik Project, which will scan cores that transect the Biwabik Iron Formation at locations along the Mesabi Iron Range.
• The International Falls Project, which will look for evidence of different types of gold mineralization within cores from a 2.7 billion year old greenstone terrane near International Falls;
• The Emily Project, which will scan cores of manganese-rich bedrock from Crow Wing County, looking for clues on how the deposits of this U.S. Critical Elements List material may have formed; and,
• The Cuyuna Project, which will examine bedrock core from the Cuyuna Iron Range, searching for mineralogical markers of potential copper-lead-zinc mineralization in Central Minnesota.
Elsenheimer said the cost to bring the mobile lab to Hibbing was
$100,000, which was actually a significant discount off the price they usually charge private industry clients.
He added that the five weeks of scanning was actually just the first stage of the project.
Elsenheimer said the raw data is currently being processed and interpreted by Corescan staff down in Australia. With terabytes of digital data to wade through, it’ll take a few months for us to get all of the final results back, and a few months more after that for DNR geologists to write up those results.
Preliminary results could be available by late spring.
“This has been a fantastic opportunity to apply cutting-edge mineral exploration technology to Minnesota’s geologic terranes. We’re using this tool on some types of mineral deposits that haven’t previously been scanned anywhere in the world, and there’s a real possibility that the results will generate global interest in both our work and in Minnesota’s mineral resources,” he said.
“That’s incredibly exciting, and something that easily makes up for all of the long hours and heavy lifting.”