No abstract

The workability, beauty, and bacteriocidal effects of silver have made it a most desirable metal since ancient times. The combination of desirable properties and the total resistance of silver to the formation of oxides has established its position as a critical metal for a myriad of advanced technology applications. Silver also imparts the properties to the many metals with which it forms commercially important alloys. Among its many important salts, the halides stand as unique photosensitive salts, providing the basis for high quality photography as well as for photochromic glass. More obscure properties of silver such as its high thermal reflectivity are also being fully exploited. For example, silver is used to provide energy‐saving domestic window glass. The unique interaction of silver and oxygen is being used to advantage in the superconductor industry. The superior fatigue resistance and lubricity of silver make it an essential component of high performance jet engines.

The workability, beauty, and bacteriocidal effects of silver have made it a most desirable metal since ancient times. The combination of desirable properties and the total resistance of silver to the formation of oxides has established its position as a critical metal for a myriad of advanced technology applications. Silver also imparts the properties to the many metals with which it forms commercially important alloys. Among its many important salts, the halides stand as unique photosensitive salts, providing the basis for high quality photography as well as for photochromic glass. More obscure properties of silver such as its high thermal reflectivity are also being fully exploited. For example, silver is used to provide energy‐saving domestic window glass. The unique interaction of silver and oxygen is being used to advantage in the superconductor industry. The superior fatigue resistance and lubricity of silver make it an essential component of high performance jet engines.

Gold is found as a relatively pure solid on the surface of the earth. It is widely distributed, but in very small concentrations. Gold is the most noble of the noble metals. Gold's properties are listed. The recovery of gold from ore is by the cyanidation process. Specifications and requirements of the international trading markets are discussed as well as precautions aganist fraud. Gold is very recyclable because of its value. Gold is benign to the enviornment, but the chemicals used in its mining are not. Gold is used in electronics, jewelery, coins, decoration, dentistry and medicine.

Gold (Au) is found as a relatively pure solid on the surface of the earth. It is widely distributed, but in very small amounts. World reserves of gold are estimated at 47,000 t.The largest reserves are found in South Africa, Australia, and Russia. Gold is the most noble of the noble metals. Gold is characterized by high density, high electrical and thermal conductivities. These properties are discussed. Heap leaching is the predominant technique for extraction of gold from it ore. The use of sodium cyanide as a leaching agent in this process is under worldwide pressure because of its negative impact on the environment. Gold is benign to the environment, but chemicals used in mining are not. Specifications and requirements of the international trading markets are given including details on precautions against fraud. Gold is most eminently recyclable material because of its value. Gold has many uses. Its main applications are in jewelry and art, electronics, and dentistry. Brazing, gold catalysts, and the use of various gold compounds are also discussed.