The economic upturn after the Franco-Prussian War of 1870-71 resulted in a renewed increase in slate production, where companies used more extensive pits. Production continued until the 1960s, when the competition from cheaper synthetic or imported slate resulted in production decline.
The economic boom after the Franco-Prussian War led to a rise in slate production, with companies expanding their mines using deeper excavations. Nevertheless, this growth was later reversed by the emergence of cheaper alternatives from other sources.