Mined to make the first compass needles, the mineral magnetite is also made by migratory birds and other animals to allow them to sense north and south and thus navigate in cloudy or dark atmospheric conditions or under water. A team of scientists has compositionally modified magnetite to capture visible sunlight and convert this light energy into electrical current. This current may be useful to drive the decomposition of water into hydrogen and oxygen. The team generated this material by replacing one third of the iron atoms with chromium atoms.