The true extent of Africa’s vast wealth of resources is hard to guess. Geologists have picked over most of the rest of the globe in search of minerals, yet huge swathes of Africa remain largely unprobed. But the immense ore deposits so far discovered and soaring commodity prices on the back of rip-roaring Chinese demand have convinced the world’s miners that the continent is the next big frontier. Bumper profits have also spurred mineral-rich countries to seek a bigger share of the spoils.