In search of Swedish lithium

It is very hard to miss the fact that Karin Högdahl studies ancient rocks, as rocks in a variety of colours and sizes line the desk, tops of cabinets, shelves and drawers of her room at the Department of Earth Sciences. Many of these contain metals such as iron, lithium and rare earth elements. A colourful geological map of Hamrånge-Bergby in Gävle reveals that she is currently leading a project studying lithium deposits.

“This particular Bergby deposit was identified as recently as 2007. We will map it and learn why the ores are where they are, along with how they are situated in the bedrock and what factors have impacted them. We also want to investigate how and whether they have any links to other types of rock. Once we know that, we will find out when these rocks were actually formed,” says Karin Högdahl.

The green transition

Lithium is needed for batteries in the green transition and demand is increasing. The prospects for finding mineable resources in Sweden are promising.

Karin Högdahl is focusing her investigations on the Gävle area, but is also curious about the situation in the northwest – in Jämtland, where she comes from.

“We’re planning to go there this summer. We’ll leave Bergby for a while and head up to Jämtland to look for lithium deposits. It's going to be really exciting. It’s got potential. The right types of rock are there,” says Karin Högdahl.

Ancient mountain ridge rich in ores

The Swedish ore deposits were formed 1.97–1.75 billion years ago, when a large mountain range was pushed up and what would become Sweden began to take shape. The so-called Svecokarelian orogeny, an ancient mountain range which has long since eroded away, stretched from the northernmost part of Sweden to the southeastern part. But how did it become so rich in ores?

“It was a special geological environment with a lot of volcanic activity. Modern examples of this type of environment are found in Japan or New Zealand. The Earth has become colder over the years, so there is no direct equivalent, but it is something along those lines. In this environment we have these iron ores containing rare earth elements, known as apatite iron ores. They are found in Kiruna, as well as central Sweden – in the Ludvika area with Grängesberg and Blötberget. They are of the same age and the same type, and it is a very unusual type of iron ore,” explains Karin Högdahl.

Pressure, heat and magma

She has long studied how the now eroded Svecokarelian orogeny was formed and how the various geological processes that have occurred since then have affected the area. It went through cycles of being pulled apart, causing molten magma to rise to the surface, and pushed together, creating pressure and heat that transformed the rocks and tipped parts of it over.

“We need to understand these structures to be able to reconstruct what things looked like, understand how the ores were formed, and determine where to target our searches. Because what I work with, it’s a bit like a white spot. If you look at these maps of where there is potential, these are areas where we already know there is something. Then there are these white spots. I don't think they’re so white, actually. I think there's more to find there. But they are simply underexplored,” she says.

Another project about to be launched and under the leadership of Karin Högdahl focuses on rare earth elements.

“A doctoral student will be looking at the ores in Grängesberg to gain a better understanding of the ore. We know that it is an ore associated with volcanic activity, but we want to learn more about its links to other geological processes,” says Karin Högdahl.

Rare earth elements not so rare

The term rare earth elements may give the impression that we are talking about elements that are extremely rare, but they are not really that unique.

“No, they're not. But it takes such special geological processes to enrich rare earth elements. Individually, they are about as common as silver if you lump them together. They occur together, although they are found in common rocks and very often are incorporated in small amounts in other minerals, but also form their own minerals with other elements,” says Karin Högdahl.

Through her research, she has seen a lot of Sweden over the years. There is one place that has a special significance to her and that she, as a researcher, thinks has something special.

“Grängesberg, the Blötberget area, probably because I worked there my first summer as a geologist – my first geological job as a part-time employee at SGU. It’s actually very close to my heart. Yes, there’s still a lot to do there,” says Karin Högdahl.

Geology gives her the answers

Curiosity has always been one of her main driving forces. Along with the desire to understand how things are connected. That is what made her decide to become a geologist.

“I had a lot of questions. I come from Östersund and spent a lot of time out in nature, right along the edge of the mountain range. The rocks of the mountain range behave completely differently from those east of Östersund. And then there is the fact that you can break the rock types apart. Why does it look like that? And the boulders... how did they get there? Then I went to Egypt and there was an obelisk that the Pharaohs had not erected. It was a granite. In my world, it shouldn’t be there. I had no idea why it was. So, I had a lot of questions. There were a lot of observations that didn’t fit in with my world view. In geology, I get the answer to this,” says Karin Högdahl.

Her career has given her both new insights and many aha moments. She is keen to share this knowledge and encourage others to enter the world of geology. This has involved everything from writing articles in the popular science magazine Forskning & Framsteg to talking about minerals in SVT’s old children's programme “Myror i brallan”.

Åsa Malmberg