Osmium - Smithson Tennant, an English chemist, discovered osmium in 1803 from the residues of platinum ores that were dissolved in nitro-hydrochloric acid. Osmium's characteristic of having a bad smell led to its naming as such, which was derived from the Greek word "osme", meaning "smell". Here, the metal is added to high-temperature nickel-based superalloys. Other uses of rhenium are as follows: 1. As catalysts in making lead-free, high-octane gasoline. 2. As filaments in making ion gauges, mass spectrographs, and photoflash lamps. 3. As electrical contact materials, due to its high resistance to arc corrosion and wear. Palladium is traded on the London Stock Exchange as an exchange-traded fund (ETF), under the ticker symbol LSE: PHPD. Platinum as an investment commodity: As of January 2010, platinum is valued at around us$1,555 per troy ounce (a couple years earlier, its price is about 48% higher than this - considered its peak price). Following is a list of some of the properties of ruthenium: General: Chemical Symbol: Ru Atomic Number: 44 Category (as an element): Transition Metal Group/ Period/ Block (in the Periodic Table): 8/ 5/ d Atomic Weight: 101.07 g.mol-1 Electron Configuration: [Kr] 4d7 5s1 Physical: Density (near room temperature): 12.45 g. Placer Mining: Three Methods Used To Mine Placer Gold The word placer, as will be found throughout here, is derived from the same Spanish word which means "sandbank". It specifically refers to an alluvial deposit of detrital material, such as gravel, which contains particles of precious chemical elements. Iridium was discovered in 1803 by the English chemist Smithson Tennant. It was identified from the residue of platinum ore which was dissolved in nitro-hydrochloric acid (also known as aqua regia). Platinum ores are still the main sources today of iridium. The precious metal is likewise obtained as a by-product of mining nickel.