Commodity prices: what copper, potash and the rest are worth

Definitions and method

The IMF publishes each series four ways: the price in dollars, an index, and two percentage changes. Only the dollar price is stored, because the other three are derived from it and a chart can recompute them. These are world benchmarks, not what any particular mine received: a producer selling on a long-term contract may never see the spot price, and for minerals with no exchange listing the benchmark is an assessed rather than a traded number.