Mader Stein

Mader Stein, or Maderstein, is a 265 m high hill in North Hesse, Schwalm-Eder-Kreis, north-east of the village of Maden, which belongs to the town of Gudensberg.

The hill is the remains of an extinct volcano that belongs to the West Hesse Depression.

The volcano was active in the Miocene, i.e. during the period about 23 to 5 million years ago. The only part of the volcano that is left is the neck; the rest has been eroded. The alkali basalt has a silica volume percentage of 45–55%. The main minerals in the rock are plagioclase, augite and olivine.

Source: Wikipedia