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Strong permanent magnets are made of a "hard" magnetic material, which is initially magnetised in a strong magnetic field. This treatment takes the magnetic material away from it's lowest energy state. These magnets will demagnetise slowly over time as they return to their lowest energy state (or immediately, if they are heated above their Curie Temperature). http://en.wikipedia.org/wiki/Neodymium_magnet#Magnetic_propertieshttp://www.ehow.com/how-does_5166377_magnet-lose-its-magnetism.html suggests that some types of magnets might lose 1% of their magnetism per decade.Magnetite is sometimes found as a "Natural" magnet, but this mineral is mostly not magnetic; some suggest it is made magnetic by a nearby lightning bolt http://en.wikipedia.org/wiki/Lodestone
http://en.wikipedia.org/wiki/Neodymium_magnetThese magnets are a glassy ceramic material Nd2Fe14B. They are usually coated with an outer layer of another more robust ceramic, because the material is reputedly quite brittle. Cigar shaped magnets like those pictured can be found on sale in toyshops etc. here.
... It's difficult to tell for certain but I think Neil's magnets are magnetite or ferrite which is pretty much a ceramic.http://en.wikipedia.org/wiki/Ferrite_(magnet)
Awesome Iron Oxide (Fe203)