Suðuroy is also the only island that contains coal in such large quantities that active coal mining has taken place.

At the time of the 1801 census, only 5,000 people lived in the Faroe Islands, and Faroese people relied primarily on peat for fuel, so there was no local interest in coal. Foreigners, however, saw opportunities in coal mining—among them Danes, who were also interested in producing coal tar, and Swedes, who hoped that valuable metals were hidden in the Faroese mountains.

These hopes were so concrete that the wealthy Swedish woman Christina von Post, who worked as an artist in Paris, together with French partners founded a French company that purchased the rights to the coal in Suðuroy. This took place in 1875. In Suðuroy, Christina von Post was commonly known as “the Coal Lady”, as she invested large sums of money in coal mining. The investors were so convinced that zinc, copper, and iron were present in the coal mines of Suðuroy that they paid substantial amounts for the mining rights. It proved to be a major disappointment when no such metals were found. Christina von Post died in 1917, destitute.

Coal mining in Suðuroy rose and fell over the years. Then, as now, the Faroe Islands were affected by global economic conditions, and the Wall Street crash of 1929 led to widespread unemployment in the Faroe Islands, as elsewhere. With assistance from local businesspeople, coal mining was nevertheless restarted. Among other things, light clay found in the coal mines was shipped to Denmark, where it was used at waterworks to soften hard water. This clay came from the coal mine in Rangabotnur.

Traces of the foreign workers who were active in Faroese coal mining over the years can still be seen in surnames found in Suðuroy. In Tvøroyri, surnames such as Wiberg, Åkeson, Persson, Ahlén, and Mårtensson can be mentioned—all of Swedish origin.