The principal sources of silver are copper, lead, zinc and gold ores. It also occurs in the minerals chlorargyrite and argentite. Of course, silver occurs natively, too. Some of the top silver-producing countries in the world are the United States, Canada, Peru, and Mexico. Fine silver, which has no less than 99.9% silver, is available commercially. Gold Standard: Definition And The Three Distinct Kinds The gold standard is defined in many different reference materials as a monetary system in which the unit of currency used is a fixed quantity or weight of gold. Under this system, all forms of money, including notes and bank deposits, were freely converted into gold at the fixed price. Two examples are given here: One is the 100,000-euro Vienna Philharmonic, minted in 2004, which contains 31 kilograms of gold; the other is the 1 million-dollar Canadian Maple Leaf, minted in 2007, which contains 100 kilograms of gold. Three factors - metal, purity, and weight - affect the value of bullion. As electrical contact materials, due to its high resistance to arc corrosion and wear. 4. As catalysts for hydrogenation of fine chemicals, because of its high resistance to chemical poisoning from phosphorus, sulfur, and nitrogen. 5. As treatment for liver cancer, because of its radioactive isotopes. The precious metal is also found - alloyed with the other metals in the platinum group as well as with gold - in Ethiopia, Australia, North and South America, and in the Ural Mountains in Russia. The Norilsk Nickel Mining and Metallurgical Company in northern Russia is the largest single producer of palladium in the world. In case the difference is negative, the seller receives payment instead from the buyer. A CFD, therefore, allows an investor to take advantage of long or short positions, enabling him/her to speculate on these markets. It must be mentioned here though that silver has lost its forced tender status in the United States since the abandonment of the silver standard, when, on August 15, 1967, then U.