Group 11 element Parkes process. These metals, especially silver, have unusual properties that make them essential for industrial applications outside of their monetary or decorative value. They are all excellent conductors of electricity. The most conductive of all metals are silver, copper and gold in that order. Silver is also the most thermally conductive element, and the most light reflecting element. Silver also has the unusual property that the tarnish that forms on silver is still highly electrically conductive. Copper is used extensively in electrical wiring and circuitry. Gold contacts are sometimes found in precision equipment for their ability to remain corrosion-free. Silver
Sydney Harbour railway electricity tunnel constructed by State Rail. The tunnel was a major technological and engineering achievement and was the first such venture to be undertaken in Australia without overseas assistance. It was a major link in the power supply to the railway and tramway system between Sydney and the North Shore and although flooded is an important element of the development of public transport in Sydney. Sydney Harbour railway electricity tunnel was listed on the New South Wales State Heritage Register on 2 April 1999. Sydney Harbour railway electricity tunnel Sydney Harbour railway electricity tunnel is heritage-listed electricity infrastructure running under Sydney Harbour