Chile produces a third of all the copper in the world. The country's economic welfare is heavily dependent on exports of the metal to Europe, the US and, increasingly, India and China.
When the copper price is low, multi-national companies like BHP Billiton, Anglo American and Xstrata - along with Chile's state-owned mining giant Codelco - account for the lion's share of production, because they are big enough to ride out the depressed prices.