mol-1 (first), 2070 kJ.mol-1 (second), 3361 kJ.mol-1 (third) Despite having higher electrical conductivity than copper, silver isn't as much used for electrical purposes as copper is. There are two reasons for this: first is that silver has a greater tendency to tarnish; and second is that silver is much more expensive. Since the late 1930s, palladium has been utilized as a precious metal in jewelry. Because of its naturally white properties, palladium has been used as an alternative to white gold. Along with silver and nickel, palladium is popularly used in making white gold alloys. According to the British Geological Survey (BGS), the top four palladium-producing countries in the world are Russia, South Africa, Canada, and the United States (in this order). 1/2 oz. coin - With a face value of USD50, 15.56 g in weight, 1.75 mm thick, and 27 mm in diameter. 4. 1 oz. coin - With a face value of USD100, 31.12 g in weight, 2.39 mm thick, and 32.7 mm in diameter. All coin varieties consist of 0.9995 fine platinum. One interesting feature of the American Platinum Eagle coin is that its reverse design changes every year. Other notable silver bullion coins include the Australian Silver Kookaburra, Chinese Silver Panda, and the Russian George the Victorious. Minting coins, whether gold or silver, always entails the risk of having the value of the metal used in the coin greater than the coin's face value. This is especially true in coins of low denomination. All other metals, including rhodium, were precipitated with zinc. Rhodium was further precipitated by the addition of sodium chloride. Finally, it was washed with ethanol and reacted with zinc, forming the precious metal that it is known today. Since rhodium occurs in ores mixed with other metals (examples: silver, gold, and platinum), its extraction is complex. These include absorption, fluorescence, X-ray, flame, visible, ultraviolet, infrared, photoemission, Mossbauer, nuclear magnetic resonance, and Raman. Again, the X-ray fluorescence (XRF) method is the modern assay method widely used today for analyzing precious metals, including (besides silver, gold, and platinum) rhenium, ruthenium, iridium, and palladium.