In the 20th century, chile's greatest source of wealth was/were

Copper mining

Large scale copper mining replaced saltpeter extraction as the country's main source of wealth.The Chilean copper mines were nationalized in the 1950's. In the Pinochet era they were transferred into the public company Codelco. Their revenue represent a large share of the Chilean government budget revenue about 20% in the 1980s. Oil mining is also another important mineral for the country.