They are used in a wide range of fields, including the automobile industry and the electronics industry, and are essential for the development of today’s advanced technology. Recently, there have been concerns in Japan about a shortage of supply of rare earths etc., and it is expected that the amounts used will increase in the future, and thus it is believed, for example, that the following measures will be necessary. There are many ways to buy into precious metals like gold, silver, and platinum, and a host of good reasons why you should give in to the treasure hunt. Precious metals can be a good portfolio diversifier and hedge against inflation – but gold, perhaps the most well-known such metal, is not the only one out there for investors. Silver, platinum, and palladium are all commodities that can be added to your precious metals portfolio, and each has its own unique opportunities. In addition to owning physical metal, investors can gain access through the derivatives market, metal ETFs and mutual funds, and mining company stocks. Rare Metals and Metalloids (RMs) are physically and chemically dissimilar to rare earth elements. However the RMs are diverse and share few overarching similarities. The critical rare metals (RMs) and metalloids discussed in this section are niobium, tantalum, cobalt, indium, zirconium, gallium, and lithium. Most of these elements are mined in substantial quantities that meet world demand. However, the few countries that possess economically viable sources of critical elements are also experiencing booms in technological industry. Bullion A metal is deemed to be precious if it is rare. The discovery of new sources of ore or improvements in mining or refining processes may cause the value of a precious metal to diminish. The status of a “precious” metal can also be determined by high demand or market value. Precious metals in bulk form are known as bullion and are traded on commodity markets. Bullion metals may be cast into ingots or minted into coins. The defining attribute of bullion is that it is valued by its mass and purity rather than by a face value as money. Purity and mass The level of purity varies from issue to issue. “Three nines” (99.9%) purity is common. The purest mass-produced bullion coins are in the Canadian Gold Maple Leaf series, which go up to 99.999% purity. A 100% pure bullion is nearly impossible: as the percentage of impurities diminishes, it becomes progressively more difficult to purify the metal further. Historically, coins had a certain amount of weight of alloy, with the purity a local standard. The Krugerrand is the first modern example of measuring in “pure gold”: it should contain at least12/11 ounces of at least 11/12 pure gold. Other bullion coins (for example the British Sovereign) show neither the purity nor the fine-gold weight on the coin but are recognized and consistent in their composition.[citation needed] Many coins historically showed a denomination in currency (example: American double eagle: $20)