Hobbies And Interests
Gold
Known as the King of Metals, gold is a highly valued precious metal. The temperature assigned to the freezing point of gold has served as a calibration point for the International Practical Temperature Scale. Gold is found in veins and alluvial deposits with calcite, copper, lead, quartz, silver, tellurium and zinc. South Africa is the world's largest gold producer. A metallic yellow color, pure gold is often alloyed with other metals, such as copper, palladium, platinum and silver. Pure gold is used to make circuit board and electrical conductors, while gold alloys are used to make coins, dental fillings and jewelry.
Silver
Silver appears in the archaeological record 5000 years ago and slag dumps dating back to 3000 B.C. suggest people were separating silver from lead in Asia Minor and on islands in the Aegean Sea. Silver is second to gold in popularity as a precious metal. It is found in pure deposits, with silver ores such as argentite and horn silver and with deposits of ores containing copper, gold and lead in Canada, Mexico, Peru and the United States. A metallic brilliant white in color, silver tarnishes easily. Silver is used to make batteries, dental alloys, electrical contacts, mirrors, photographic film and solder and brazing allows. Sterling silver contains 92.5% silver, and is used to make jewelry, silverware and decorative items.
Platinum
First used by the pre-Columbian Indians of South America, Antonio de Ulloa is credited with the modern discovery of platinum in 1735. It is the rarest and most expensive precious metal, and is found in alluvial deposits in Columbia, the Ural mountains and the western United States with traces of other precious platinum group metals, including iridium, osmium, palladium, rhodium and ruthenium. Silvery-white in color, platinum is resistant to corrosion. It is used in dentistry and to make catalytic converters, electrical contacts, laboratory vessels, jewelry and wire.
Palladium
English chemist William Hyde Wollaston discovered the precious metal palladium in 1803 while analyzing platinum ore samples from South America. He named it after the Pallas asteroid. A rare element, palladium is found in placer deposits in Australia, Canada, Ethiopia, North America, Russia, South Africa and South America with platinum and other platinum group metals, including copper, gold, nickel and silver. It is steel white in color, and is the least dense of the platinum group metals. Palladium is used to make dental fillings and crowns, electrical contacts, surgical instruments and watch springs. Palladium alloys are used in jewelry.