Iron ore mining activities started on the island of Utö already in the 12th century and continued for 700 years. The business reached its largest scale in the early 1600s. This is when Finngruvan (“The Finn Mine”, ore from which was delivered to cabins in Finland) and Långgruvan (“The Long Mine” with an oblong shape) were taken up. The path leads between these two, both are now filled with water and look more like small lakes rather than mines. 

Nyköpingsgruvan Photo: Stadsfiskal Lars Stendal 1892

In total, there were nine mines in operation and about 2.5 million tonnes of ore were mined here. The largest and the deepest (215 meters) of the later created mines was Nyköpingsgruvan (”Nyköping Mine”), also called Storgruvan (“The Big Mine”). The ore from this mine was delivered to settlements outside Nyköping. Working conditions in the mines were far from attractive. The working day started at 5 a.m. and lasted until late evening. The work was dangerous and accidents were common. There was a shortage of labor, so tramps and criminals were shipped to the island to work in the mines. 

Iron ore was for sure the main treasure on this island, but not the only one. There was a silver mine as well, opened in 1607 for extraction of silver-containing lead. The hole of this mine is still visible.

Utö has also become famous in the scientific world as the home of Holmquistite - a lithium magnesium aluminium inosilicate mineral, found only on Utö. It was named after the Swedish geologist and petrologist Per Johan Holmquist.

The mines were closed in 1878. The mining company arranged a farewell dinner outside, by the mines. When the party was over, the plates, glasses and silverware were thrown into the darkness of the mine along with tables and chairs.