 42 out of a total 50 claims active at the time in the Spessart region were located in the upper Kahl valley, 11 of them in Sommerkahl.From the late 19th century, the "Grube Wilhelmine" was active with copper being mined in several tunnels.Today, access is limited to a depth of around 23 meters, but when active, mining took place at up to 40 meters.