Brass than in brass produced by cementation. These may be "natural alloys" manufactured by smelting zinc rich copper ores in redox conditions. Many have similar tin contents to contemporary bronze artefacts and it is possible that some copper-zinc alloys were accidental and perhaps not even distinguished from copper. However the large number of copper-zinc alloys now known suggests that at least some were deliberately manufactured and many have zinc contents of more than 12% wt which would have resulted in a distinctive golden color. By the 8th–7th century BC Assyrian cuneiform tablets mention the exploitation of the "copper of the mountains"
Metal and Machinery Workers Industrial Union Metal and Machinery Workers Industrial Union The Metal and Machinery Workers Industrial Union No. 440 (MMWIU) was a labor union in the United States which existed between 1907 and 1950. It organized workers in the manufacturing industry and was affiliated with the Industrial Workers of the World (IWW). The earliest recorded local of the MMWIU was in Bridgeport, Connecticut in 1907. A number of machinists' locals were also active under the IWW around that time, which dated from a period when a large number of craft union locals were switching their affiliation to the IWW, and whose organizational structure did