Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Rare earth minerals are found in and essential to most modern machines - powerful rare earth magnets have dramatically reduced the size of modern electronic devices, and most green technologies, such as hybrid cars and wind turbines would not be possible without them. For example the battery of Toyota Prius contains around 15 kilograms of the rare earth element lanthanum and the magnet in a large wind turbine may contain 220 or more kilograms of neodymium. Though not as rare as the name suggests, the demand for rare earths is rising in such speed that it may soon outstrip the supply. Learn more about this little-known, but essential class of elements in this book.