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If i am placing two rock(stone) chips closer with a wider area of contact and rotating another rock stone around these two chips(having close contact) for some time (around 30 sec) and try to separate the two stones that i put into contact at first, it seems there is an attraction between the two. Why this is happening? Please explain the phenomenon behind it.

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The stone contains a ferromagnetic material, which is a material with a spontaneous magnetization. In thermal equilibrium, such a material aligns itself to be magnetized in the same direction. But over a very large distance, you can reduce the bulk energy by randomizing the field direction, so that it pays to put in very large domain walls separating different magnitization regions.

When there is an external magnetic field, it makes the domains line up. The dynamics of the domains is extremely slow, so you end up with a magnetized rock. You are seeing magnetization caused by placing a ferromagnet in the magnetic field of another. You don't need to rotate to see this, just hold them close and wait.

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Thank you for the reply.. So the rock is having curie temperature above the room temperature, isn't it? please let me know whether the same property is shown for the other ferromagnetic materials like Fe, Co, Ni etc.. – arun Nov 26 '11 at 11:55
The Curie temperature is usually a significant fraction of the melting temperature, which for metals is thousands of degrees. The reason is that the electron spin aligning forces are of the same order of magnitude as the solid cohesion forces (a little weaker, but not much). It's surely many hundreds of degrees for everything you listed, although I didn't look it up. – Ron Maimon Nov 26 '11 at 12:20
""The stone contains a ferromagnetic material, "" How did You find out that? Aside from the very strange description of "magic rotations" I find not hint to ferromagnetism. – Georg Nov 26 '11 at 13:13
@Georg Here we see that the average rock has about 5% oxides of iron. That is enough for the iron to acquire a magnetization when sitting still for ages, from the earth's field, and display it broken in small chips. – anna v Nov 26 '11 at 14:26
""that the average rock has about 5% oxides of iron. That is enough for the iron to acquire a magnetization when sitting still for ages, "" This is 1st wrong, and 2nd not at all a clue for ferromagnetism. – Georg Nov 26 '11 at 14:41

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