Steinbruch Donnerkuhle, Limestone quarry in Hagen, Germany.

The Donnerkuhle quarry is a 67-hectare open-pit dolomitic limestone operation near the Hohenlimburger Straße in Hagen, run by Rheinkalk (Lhoist Group). Its walls expose Massenkalk formed about 370 million years ago in the Middle Devonian, partly altered to dolomite by magnesium-bearing waters. Two viewpoints with information boards lie outside the operating area.

Mining at Donnerkuhle started in the early 20th century and became crucial to Hagen's industrial growth. The operation developed into a major supplier of limestone for construction materials and chemical production over many decades.

The quarry's name, Donnerkuhle, is echoed in a verse on a GeoPark Ruhrgebiet information board outside the site, which rhymes the slow formation of dolomite from limestone with its later extraction. The board also marks the planned expansion area toward Haßley and its future recultivation. A works choir, the MGV Sangesfreunde der Dolomitwerke, was founded on 9 October 1949 for the employees.

The quarry is an active industrial site operated by Rheinkalk (Lhoist Group); access is limited to two viewpoints with information boards outside the operating area, near the Hohenlimburger Straße (B7). The quarry covers about 67 hectares, so the rock faces are seen from a distance rather than up close.

The quarry walls contain limestone formations dating back about 370 million years to the Middle Devonian period. These ancient deposits were modified by mineral-rich solutions rising through geological faults, which altered their appearance and character.