Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A samarium-cobalt magnet, one of the two types of rare earth magnet, is a strong permanent magnet made of an alloy of samarium and cobalt. They were developed in the early 1970s. They are generally the second-strongest type of magnet made, less strong than neodymium magnets, but have higher temperature ratings. They are expensive, brittle, and prone to cracking and chipping. Samarium-cobalt magnets have maximum energy products (BHmax) that range from 16 megagauss-oersteds (MGOe) to 32 MGOe; their theoretical limit is 34 MGOe. They are available in two "series", namely Series 1:5 and Series 2:17.