It was discovered by the English chemists William Hyde Wollaston and Smithson Tennant in London, England in 1803. Wollaston's and Tennant's discovery of the element involved the discovery as well of the other elements in the platinum group. With an average mass fraction of 0.05 parts-per notation in the continental crust, osmium is known to be one of the least abundant elements in the Earth's crust. mol-1 (third) Palladium is used in the following: 1. Catalytic converters; 2. Jewelry and watch making; 3. Dentistry and surgical instruments; 4. 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. Here are some of the properties of gold: General: Chemical Symbol: Au Atomic Number: 79 Category (as an element): Transition Metal Group/ Period/ Block (in the Periodic Table): 11/ 6/ d Atomic Weight: 196.966569(4) g.mol-1 Electron Configuration: [Xe] 4f14 5d10 6s1 Physical: Density (near room temperature): 19.30 g. But while platinum is generally resistant to corrosion, it is corroded by certain elements, such as cyanides (potassium cyanide or sodium cyanide), caustic alkalis, sulfur, and any of the five halogens (astatine, bromine, chlorine, fluorine, and iodine). The following lists some of the properties of platinum: General: * Chemical Symbol: Pt * Atomic Number: 78 * Category (as an element): Transition Metal * Group/ Period/ Block (in the Periodic Table): 10/ 6/ d * Atomic Weight: 195.084 g. The ranking appears different when the estimated world market prices, per troy ounce, of these nine precious metals are considered (estimates as of January 2010): 1st: Rhodium - USD2,750 2nd: Platinum - USD1,555 3rd: Gold - USD1,131 4th: Palladium - USD424 5th: Iridium - USD408 6th: Osmium - USD380 7th: Rhenium - USD194 8th: Ruthenium - USD173 9th: Silver - USD18 Of the nine precious metals, gold and silver are the best known. In fact, it is known to be more versatile than any of the other five precious metals in the platinum group. A hard, white metal, ruthenium is known to have four crystal modifications. While it does not tarnish under normal temperature, it does oxidize readily when exposed to air. It can be plated by means of two methods: thermal decomposition and electrodeposition.