Platinum - This element, after which this group of precious metals is named, is represented by the symbol Pt. Its atomic number is 78. Platinum is dense, ductile, and malleable; it is gray-white in color. Known to be highly resistant to corrosion, this precious metal is used in jewelry, electrical contacts, and laboratory equipment. In earlier times, precious metals were mainly used as currency. Today, however, they are highly regarded as investment and industrial commodities. Four of them, in fact - silver, gold, platinum, and palladium -, are minted into coins or cast into ingots and traded on commodity markets. All four are assigned the ISO 4217 currency code. These coins contain 90% silver and are 8/10 troy ounce per 1 USD of face value. Buying silver bullion bars: This is the most traditional way of investing in silver. Silver bullion bars can be bought or sold over the counter in most banks in Switzerland. They may be stored in safe deposit boxes in banks or placed in non-fungible (allocated) or pooled (unallocated) storage with a silver dealer. General: Chemical Symbol: Ag Atomic Number: 47 Category (as an element): Transition Metal Group/ Period/ Block (in the Periodic Table): 11/ 5/ d Atomic Weight: 107.8682 g.mol-1 Electron Configuration: [Kr] 4d10 5s1 Physical: Density (near room temperature): 10.49 g.cm-3 Liquid Density (at melting point): 9.320 g. The lines, which represent equilibrium for the concentration, are drawn for ions at unit activity. Other concentrations may be represented by additional lines. The voltage potential is represented by a vertical axis, which is labeled Eh, where "h" stands for hydrogen. Physics has an even more strict definition for noble metals. Rhenium: Last Naturally Occurring Stable Precious Metal Discovered In the periodic table of elements, rhenium is found as a third-row transition metal in group 7. Known to be one of the rarest precious metals in the Earth's crust, rhenium has an average concentration of 1 part per billion. It is obtained mainly as a by-product of the refinement of two other chemical elements - copper and molybdenum.