Ore bodies, it has been discovered, are not randomly distributed

AS TREASURE MAPS go, it will be hard to beat. Geologists from Harvard University, Geoscience Australia and the Australian National University are drawing up a map to show where mining companies should focus their search for the ores of metals such as lead, nickel, copper and zinc. The billions of dollars they spend exploring for these minerals ($8.4bn in 2017) should, the researchers behind the project say, be aimed at the edges of old, thick portions of the continents called cratons.The map itself will be published soon in a peer-reviewed journal. But the theory behind it was outlined on April 9th by Fred Richards, of Harvard, at a meeting in Vienna of the European Geosciences Union. The project started with an attempt to make a detailed map of the thickness of Earth’s lithosphere (its crust and upper mantle). The researchers thought this might have something to do with the distribution of sediment-hosted deposits, a particular type of ore body. Such deposits are created by water percolating up through consecutive layers of rock that have different chemical properties.