Thorium is a chemical element with the symbol Th and atomic number 90. It is a naturally occurring, slightly radioactive metal that is found in rocks, soils, and minerals. Thorium has a number of unique properties that make it useful for various purposes, including nuclear energy, scientific research, and certain types of lighting. In particular, thorium is being explored as a potential alternative to uranium as a fuel source for nuclear reactors because it is more abundant, more efficient, and produces less radioactive waste. However, thorium is also a known carcinogen and can be dangerous if not handled properly. Its use is therefore tightly regulated by governments around the world.