Ferrite magnets were once the strongest magnets in existence until rare earth magnets were discovered, and in many instances their more powerful cousins have replaced them. However, this ferrite magnet is much less brittle and is considerably cheaper and easier to get hold of than rare earth magnets, and it is made from a mixture of a ceramic material and iron (III) oxide. Some iron ore (magnetite) is magnetic from the moment it is extracted from the ground, but this iron (III) oxide largely comes from the ore hematite, which is not strongly magnetic and has to have its magnetic field enhanced during the production process. To do this, the magnet’s constituent materials are heated to a critical temperature and allowed to cool in the presence of a magnetic field.
Magnetic iron oxides have a long history of use by humans with naturally occurring magnetised ‘lodestones’ (magnetite) used in navigation as primitive compasses since the 12th Century. Compasses work by the principle that the earth itself has a magnetic field, and the magnetised free-moving needle or pointer aligns itself with that field, with one end pointing towards the south magnetic pole, and the other to the north magnetic pole.
Sample ID: 86
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