It is also considered one of the rarest precious metals. Palladium closely resembles its co-member in the platinum group - platinum. It is soft and is silvery-white in color. Like rhodium, palladium is largely used as a catalytic converter. As of January 2010, the price of this metal is estimated to be approximately USD424 per troy ounce (USD13,632 per kilogram). With the use of a spectrometer or spectrograph, the amount or concentration of a given substance is assessed. The substances are identified through the spectrum they absorb or emit. This assay method has several types. These include absorption, fluorescence, X-ray, flame, visible, ultraviolet, infrared, photoemission, Mossbauer, nuclear magnetic resonance, and Raman. Bullion is traded on commodity markets in two forms: bulk ingots or coins, the latter minted by the government of a country. At least ten countries are known to mint gold and silver bullion coins. These are Australia, Austria, Canada, China, Mexico, Poland, South Africa, Switzerland, the United Kingdom, and the United States. Rhodium is likewise used in jewelry, such as when it is electroplated on platinum, sterling silver, or white gold (called rhodium flashing) to strengthen the metal or give it a reflective surface. Rhodium has at least five other uses or applications: 1. As an alloying agent, to improve platinum's resistance to corrosion. A silver account is backed through either allocated or unallocated storage. Owning a silver certificate: In lieu of storing actual silver bullion, an investor may opt for ownership of a silver certificate. A silver certificate allows an investor to buy and sell the security sans the inconveniences associated with the physical silver's transfer. continues to import a big part of its total consumption of the precious metal from some of the countries mentioned above. Since rhenium and its compounds are used in very small amounts, very little is known about their toxicity. So far, only a few rhenium compounds have been tested for toxicity, and these include rhenium trichloride and potassium perrhenate.