The process involves reduction of ammonium ruthenium chloride with the use of hydrogen. This yields a powder which, in turn, is consolidated by means of a technique called argon-arc welding. In terms of abundance in the Earth's crust, ruthenium ranks 74th among all the different known elements or metals and is, therefore, one of the rarest. Platinum is traded on the London Stock Exchange (as ETF, under the ticker symbol LSE: PHPT) and on the New York Mercantile Exchange. One way of investing in platinum is through platinum ingots. Platinum ingots are first assayed and hallmarked before being sold on commodity markets. Another way of investing in platinum is through platinum coins. Its other physical characteristics include its being malleable, ductile, and dense. 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). Under these two factors, nine metallic chemical elements qualify as precious metals. These are, in no particular order, gold, palladium, silver, rhodium, iridium, ruthenium, platinum, osmium, and rhenium. So that while the chemical element tellurium is considered one of the rarest element in the Earth's crust (its mass abundance being the same as that of rhodium, iridium, and ruthenium), its estimated price is only less than 5 U. The gold certificate allows the investor to buy and sell the security and do away with the many difficulties associated with the actual gold's transfer. Trading in Gold Exchange-Traded Funds (GETFs): Trading in GETFs is like trading shares in, say, the New York Stock Exchange or the London Stock Exchange. 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.