The Morning Star Mine's processing mill stood on foundation pillars at this site and, during the World War I mining boom, rising zinc prices allowed the company to expand and modernize it until it could crush and separate 200 tons of zinc ore a day. Inside the mine, powdermen and drillmen dug the ore, shovelers loaded it into ore cars, and car men pushed the cars to the mine entrance, where mule teams pulled them along the tramway to a storage hopper until the mill needed more. The ore then moved by tramway to the mill, where machiners, jigmen, and helpers crushed, rolled, and screened it and separated the metal from the rock, after which the zinc was stacked for shipment to buyers. The mill had opened in 1898 with a steam boiler fueled by wood from the surrounding hillsides powering a 50-ton-a-day ore crusher, and by 1918 it used huge jaw crushers and advanced concentration tables to process 200 tons a day. After the war ended and zinc was overproduced, its value fell sharply. A typical Rush milling crew included woodmen, firemen, jigmen, jig tenders, and engineers, who worked 10-hour days five to six days a week for 20 to 35 cents an hour.