Qualla: Pyhäsalmi Mine

Pyhäsalmi Mine: Introduction

Fri, 27 Mar 2026 00:00:00 GMT

Photo credit Tiia Monto, CC BY-SA 3.0. Fourteen hundred meters below the forests of central Finland, there is a sauna. It is the deepest sauna in the world, heated in tunnels carved through rock that formed nearly two billion years ago. The sauna belongs to the Pyhäsalmi Mine in Pyhäjärvi, a zinc and copper operation that burrowed into the Earth for sixty years starting in 1962 and reached 1,444 meters, making it the deepest base metal mine in Europe. But the most remarkable thing about Pyhäsalmi is not how deep it goes. It is what happens down there after the miners leave.

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Image: Tiia Monto | CC BY-SA 3.0

Pyhäsalmi Mine: From a Farmer's Well to Europe's Depths

Fri, 27 Mar 2026 00:00:00 GMT

Photo credit Usv at English Wikipedia, CC BY 3.0. The mine exists because a local farmer dug a well in 1958 and struck something unusual: gossan ore, the oxidized cap of a massive sulfide deposit. He sent a sample to Outokumpu Corporation, and the geological survey that followed revealed a rich volcanogenic massive sulfide depos...

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Image: Usv at English Wikipedia | CC BY 3.0

Pyhäsalmi Mine: A Second Life Underground

Fri, 27 Mar 2026 00:00:00 GMT

Photo credit Usv at English Wikipedia, CC BY 3.0. As the ore body neared exhaustion, the town of Pyhäjärvi and the University of Oulu launched Callio, a project to transform the mine into something entirely new. The ambitions are wide-ranging. The Callio Lab hosts a physics laboratory studying cosmic rays and neutrino interactio...

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Image: Usv at English Wikipedia | CC BY 3.0

Pyhäsalmi Mine: Growing Food Where Sunlight Cannot Reach

Fri, 27 Mar 2026 00:00:00 GMT

Photo credit Usv at English Wikipedia, CC BY 3.0. Some of Callio's most inventive projects sound like science fiction. At 660 meters underground, the Natural Resources Institute of Finland grew hops using hydroponic technology, testing whether year-round production in controlled conditions could replace seasonal outdoor harvests...

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Image: Usv at English Wikipedia | CC BY 3.0

Pyhäsalmi Mine: Power from the Deep

Fri, 27 Mar 2026 00:00:00 GMT

Photo credit Tiia Monto, CC BY-SA 3.0. In late 2022, the European Union approved 26.3 million euros for a pumped hydroelectric energy storage facility inside the mine, a 530-megawatt-hour system designed to store renewable energy by pumping water between underground chambers at different depths. The concept is elegant...

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Image: Tiia Monto | CC BY-SA 3.0