R is for many things: Rockhouse, Rocks, Rock hammer, Ruins, and Railroad. This scene is R-eriffic!
This is the ruin of the rockhouse of the Mohawk #6 mine. A towering steel structure used to sit on this foundation, where copper-bearing rocks from the mine would be sorted, crushed, and sent off to the mill. A railroad spur used to run straight through this cut in the rockhouse. The large tower in the center is the foundation for the rock hammer, which would break rock loose from chunks of copper. The rock hammer was located very high up, so that the broken rocks could be sent to lower levels using gravity.
This is the same sort of structure as the Isle Royal #6 rockhouse, which I photographed with star trails last week.