In the 1940s, the smelter, by then shut down, was converted into a uranium mill for processing the materials that would be used in the bombs dropped on Hiroshima and Nagasaki in 1945. It continued as a uranium mill until 1963. Note the huge pile of uranium tailings behind the smokestack. In the foreground is the Santa Rita neighborhood -- aka "The Flats." And that train was probably headed to Alamosa via Chama.
Jonathan P. Thompson 