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
Simple commodity production persists within industrialised capitalist economies in the form of self-employment by free producers. Capitalist firms sometimes contract out specialised services to self-employed producers, who can produce them at a lower cost, or provide a superior product. In Marxian political economy, simple commodity production also refers to a hypothetical economy used to interpret some of Karl Marx's insights about the economic laws governing the development of commodity trade: it refers to a market economy in which all producers own the resources (including the ability to work) that they use in production. No-one is a proletarian, selling his or her labor power