Aircraft spark plugs; 5. Electrical contacts; 6. Connector platings; 7. Manuscript illumination. 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. Because it was first chanced upon in silver mine in South America, platinum was named as such, after the Spanish word "platina", which translates to "little silver". 2. Palladium - William Hyde Wollaston, an English chemist and physicist, discovered palladium in 1803 in samples of platinum ore obtained from South America. Silver coins may either be "fine silver" or "junk silver". Junk silver coins are older coins with a lower percentage of silver. Examples of these are the dime, quarter, and fifty-cent U.S. coins minted in 1964 or earlier. These coins contain 90% silver and are 8/10 troy ounce per 1 USD of face value. Along with the five other precious metals in the platinum group, ruthenium is generally found in ores in North America, South America, and the Ural Mountains in Russia. Small quantities of this element also occur in pentlandite (an iron-nickel sulfide) obtained from Sudbury in Ontario, Canada, and in South Africa's pyroxenite (an ultrabasic igneous rock) deposits. Using the "aqua regia" test (aqua regia is a mixture of concentrated nitric acid and concentrated hydrochloric acid, which is highly corrosive), here's how the eight precious-noble metals react: Gold, platinum, palladium, and osmium dissolve. Ruthenium dissolves only in the presence of oxygen. Silver coins, like the minted coins circulated in the United States and other countries prior to 1965, were made of 90% silver and 10% copper. The American Silver Eagle and the Mexican Silver Libertad bullion coins, introduced in 1986 and 1982 respectively, were made of 99.9% silver and 0.1% copper. Other notable silver bullion coins include the Australian Silver Kookaburra, Chinese Silver Panda, and the Russian George the Victorious.
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