Iron, nickel, cobalt and manganese are the only four metals considered magnetic. All other metals, including gold, silver and aluminum, are typically considered non-magnetic, although there are some elements that may show a slight positive or negative attraction when placed in a magnetic field.
The elements that show a slight attraction to a magnetic field are known as paramagnetic substances. Aluminum, tin and oxygen are some of the examples of paramagnetic elements. On the other hand, elements that show a slight negative reaction or are repelled by the magnetic field are referred to as diamagnetic elements. This group includes copper, hydrogen, bismuth and graphite.
Most magnets are made from one of the four magnetic metals, which are collectively referred to as the ferromagnetic metals. However, alloys of these ferromagnetic metals mixed with rare earth minerals are also commonly used to create magnets. A magnet is created by heating a ferromagnetic metal or alloy past its specific Curie temperature, the temperature at which the metal takes on magnetic properties. The ferromagnetic metals contain many small magnetic fields that become aligned together to create one field when the metal reaches its Curie temperature.
Over time, these smaller magnetic fields, known as domains, can eventually fall out of alignment as the magnetism isn't permanent. However, the magnetic effects can be made more permanent by heating the metal well past its Curie temperature.