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 rent, profit, labour and the costs of wear and tear on the instruments of husbandry. David Ricardo, a follower of Adam Smith, modified Smith's approach on this point by alleging that labour alone is the content of the exchange value of any good or service. While maintaining that all exchange value in commodities was derived directly from the hands of the people that made the commodity, Ricardo noted that only part of the exchange value of the commodity was paid to the worker who made the commodity. The other part of the value of this particular commodity was labour that