Precious metal "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. 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
Commodity money a legal code. Several centuries after the invention of cuneiform script, the use of writing expanded beyond debt/payment certificates and inventory lists to codified amounts of commodity money being used in contract law, such as buying property and paying legal fines. Today, the face value of specie and base-metal coins is set by government fiat, and it is only this value which must be legally accepted as payment for debt, in the jurisdiction of the government which declares the coin to be legal tender. The value of the precious metal in the coin may give it another value, but this