|MadSci Network: Earth Sciences|
Materials that are said to be ferromagnetic, such as magnetite, get their magnetic properties from an ordering of atoms (or molecules). Within a large piece of ferromagnetic material, the ordering of atoms (or molecules) gives rise to regions called domains within which all the atomic magnets are oriented similarly, resulting in a stronger magnetic effect. Also, in a large piece of ferromagnetic material that exhibits magnetic properties, the many domains are similarly oriented. When you combine particles of magnetite, each particle might still have all its domains similarly oriented, but those of neighboring particles would have domains oriented in other directions. So, while the individual particles may still exhibit magnetic properties, the collection of particles with randomly oriented magnetic fields would not because the fields of one particle would be countered by the fields of its neighbors. Most high-school and college physics textbooks should have a discussion of ferromagnetism. In addition, while searching the web, I found the following sites you may be interested in visiting; [about magnetite] http://mineral.galleries.com/minerals/oxides/magnetit/magnetit.htm [about ferromagnetism] http://www.treasure-troves.com/physics/Ferromagnetism.html Thanks for your question. sid
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