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October 30, 2023

Hundreds of years ago, cobalt was thought to be a goblin that ruined silver mines and made miners ill. Now it’s a valued mineral commodity in its own right, and an illustration of the value of mine waste research.

Deep in the dark mines and forests of Germany, in the days long before electricity when flickering torchlight made shadows come to life, whispers told of mysterious and ominous creatures waiting to prey on the hapless and unaware. One of these, the Kobold, was a particular bane of German silver miners, poisoning their silver ore so that the metal that emerged was mere powder, not the lustrous ingots they sought. The Kobold even poisoned their bodies, making them retch and sapping their strength. The miners cursed the Kobold or sometimes even made offerings to the Kobold to stave off its mischief, but to no avail. 

Image: Biotitic Mafic Dike at the Blackbird Cobalt-Copper Mine
Dark shadows lurk even in modern cobalt mines like this one in Idaho. Photo Credit: Ark Bookstrom, USGS.

Today, we know why those miners were afflicted—instead of a malicious goblin, the miners had unintentionally encountered the element cobalt. In contrast, we now specifically seek out cobalt. Cobalt is an essential component of many rechargeable batteries, making it an important part of the renewable energy transformation, electric vehicles and modern electronics. It’s also a crucial element for many superalloys for the aerospace industry, defense industry and manufacturing. We’ve even added it to our list of Critical Minerals. A far cry from the hated goblin of yore. 

But the story of cobalt’s migration from hated demon to desired commodity mirrors that of many elements. As the number of elements required for our modern economy grows, so does the need to produce them from minerals. In many cases, though, these elements are only required in small amounts, making them difficult to mine profitably on their own. As a result, most are produced alongside more traditional metals like copper, gold and iron, and are called byproducts. 

Image: Discarded Drill Cores from the Blackbird Cobalt-Copper Mine
Mine tailings from the Blackbird copper-cobalt mine. Not what you'd want in your trick-or-treat bag, but of significant interest for us for potential leftover mineral byproducts.

At the USGS, we’ve been studying byproduct minerals both in the initial production of primary metals as well as increasing our focus on revisiting mine waste. Mining produces a lot of waste. Ore, the part of the rock that contains a potentially profitable concentration of a particular mineral commodity, is usually a relatively small percentage of the overall rock that is mined. The leftovers are called tailings and are frequently discarded and stored at the mine site, while the ore is taken away to be processed into the mineral. Mine waste also includes the topsoil, waste rock and other materials that were removed to get to the ore. 

During historical mining, as in the German silver and copper mines mentioned above, the focus was on the metals that were valued at the time. There was no interest in the other elements that interfered with obtaining the silver or copper like cobalt, or even arsenic--which frequently occurs alongside cobalt and was the cause of the illnesses in the German miners. Now that we are interested in the cobalt for its own sake, there’s value in returning to the mine waste to see what cobalt resources remain in the abandoned waste.  

We’re also interested in learning how to mitigate the harmful effects of cobalt mining. Although it was largely arsenic that caused the health problems for the German miners who named the Kobold ore, cobalt itself is known for causing significant health effects. In some countries like the Democratic Republic of the Congo, there are real concerns about the health of some of the artisanal miners for cobalt. We are working with the U.S. Department of State, U.S. Agency for International Development, United Nations and other governmental and nongovernmental organizations to address these issues. In the United States, we’re looking at the environmental impacts of legacy cobalt mining as well as what methods can work for mitigating those impacts from future mining.  

Image shows a sample of cobaltite
A sample of Cobaltite, one of the primary ores for cobalt. Image credit: Smithsonian National Museum of Natural History.

So as you make your Halloween dance videos or take pictures of your favorite costumes in the flickering candlelight from jack-o'lanterns, remember that some of the elements that make your smartphone function used to be just as feared in the flickering torchlight of the mines.

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