Like rhodium, palladium is largely used as a catalytic converter. As of January 2010, the price of this metal is estimated to be approximately USD424 per troy ounce (USD13,632 per kilogram). 4. Osmium - This element is represented by the symbol Os. Its atomic number is 76. It is found in nature as an alloy in platinum ores. It specifically refers to an alluvial deposit of detrital material, such as gravel, which contains particles of precious chemical elements. The term "placer gold", therefore, refers to gold that has formed in rocks moved and placed on stream beds by some geological forces and by the action of water. mol-1 Electron Configuration: [Kr] 4d8 5s1 Physical: Density (near room temperature): 12.41 g.cm-3 Liquid Density (at melting point): 10.7 g.cm-3 Melting Point: 1964 C, 3567 F, 2237 K Boiling Point: 3695 C, 6683 F, 3968 K Heat of Fusion: 26.59 kJ.mol-1 Heat of Vaporization: 494 kJ.mol-1 Atomic: Oxidation States: 6, 5, 4, 3, 2, 1, -1 Electronegativity: 2.28 (Pauling scale) Atomic Radius: 134 picometre Covalent Radius: 142 7 picometre Ionization Energies: 719.7 kJ. He named this precious metal after "ruthenia", the Latin word for Klaus's home country Russia. 7. Rhenium - A team of German chemists, composed of Walter Noddack, Ida Tacke, and Otto Carl Berg, discovered rhenium in 1925. They discovered the element from platinum ore samples as well as from the mineral gadolinite. There are three known kinds of gold standard that have been adopted since the early 1700s - the gold specie, gold exchange, and gold bullion standards. Following is the definition and a brief historical account of each. Gold Specie Standard: In this gold standard, the unit of currency is linked to the gold coins that are in circulation. On the average (considering the consistent rise in the exchange rate of gold), the value of gold is around USD12 per gram. Here, it is clear that the currency value assigned by the government to a gold bullion coin has no meaning. Below is a list of some of the government-issued gold and silver bullion coins: 1.