Is Gold Magnetic?
Most recent answer: 5/11/2018
- shawn johnson
winchester, ma, usa
Shawn -
Pure gold is not magnetic. That is, it doesn’t form a magnet on its own. If you put it in a magnetic field it will magnetize a tiny bit, but only so long as it’s in the field. and the direction of the magnetizaqtion makes it weakly repel the magnet.
There are alloys of gold, for example gold with more than about 20% of the atoms replaced by iron, which do magnetize on their own, at least when they are very cold, much colder than room temperature.
-Tamara (w Mike)
(published on 10/22/2007)
Follow-Up #1: magnetic panning for gold
- shawn johnson
winchester, ma, usa
Shawn- I guess the answer is just that the gold magnetizes so little even in a strong field that you can’t pick it up. You may not have much pure gold lying around, but you probably have some copper wire, which has similar magnetic and electrical properties. Your son can try picking it up with a magnet. No answer beats a nice experiment.
Mike W.
p.s. It turns out gold and copper are very weakly diamagnetic, which means they'll be slightly repelled by the magnet, unless they have magnetic impurities in them.
(published on 10/22/2007)
Follow-Up #2: Using magnets to pick up gold
- Andrew (age 21)
Bellevue Community College, WA
There is a version of this which may be more successful, though. If the magnetic field is both non-uniform and alternates in time, then the magnetic field will generate eddy currents in the electrically conductive gold flakes. These eddy currents will oppose the change in magnetic field, and the net effect will be to repel electrically conducting flakes from the alternating magnetic field. There may be other kinds of electrically conducting flakes in your sample, but gold is one of the better electrical conductors, and this level of separation may already be a big step forwards.
Tom
(published on 10/22/2007)
Follow-Up #3: magnetic silver?
- Anonymous
Mike W.
(published on 10/22/2007)
Follow-Up #4: Gold and magnets... almost no attraction
- Lacy (age 24)
Winston-Salem, NC USA
Magnets strongly attract materials (like iron) which already themselves have magnetic domains. They do not significantly attract many metals like gold, aluminum, silver, and even some types of high-chromium stainless-steel, which lack such domains. In fact, pure gold is slightly repelled. A metal detector, if sensitive enough, should pick up the signal from a gold ring.
LeeH and Mike W.
(published on 10/22/2007)
Follow-Up #5: Magnetic test for gold?
- Anonymous
LeeH
(published on 11/07/2009)
Follow-Up #6: magnetic classification
- Jessica (age 12)
Singapore
Mike W.
(published on 09/05/2010)
Follow-Up #7: does a magnet stick to gold?
- ononomis (age 11)
fl.
Mike W.
(published on 07/24/2011)
Follow-Up #8: magnets picking up gold coins?
- Ted Sudol (age 62)
Ringwood
You're confused? How do you think we feel?
One thing that one might think- that the weak paramagnetism of simple models of metals could be involved- doesn't work because gold is slightly diamagnetic.
There seem to be several possibilities:
1. The coins have magnetic impurities.
2. The magnets are electromagnets and use some tricky spatial pattern of ac fields to use eddy currents to pull up the conducting coins. (Simple patterns would repel the coins.)
3. There's some sort of hoax.
Mike W.
(published on 03/31/2012)
Follow-Up #9: coins: loonies and toonies
- Richard E (age 28)
Calgary Albert canada
Mike W.
(published on 06/03/2012)
Follow-Up #10: magnets weakly repel gold
- deborah (age 50)
fla
We say repeatedly in this thread that magnets do not attract gold. In fact, they repel it very weakly.
Mike W.
(published on 08/13/2013)
Follow-Up #11: Canadian coins: gold?
- Antonio (age 24)
zapopan
Those coins aren't really gold. See above.
An ac electromagnet will repel gold, because of the eddy currents.
Mike W.
(published on 09/11/2014)
Follow-Up #12: why so many repeat questions?
- Benedict (age 32)
Spain
I don't know.
Mike W.
(published on 04/12/2015)
Follow-Up #13: gold affecting magnets?
- Robert C Kahlert (age 48)
Leander
This does indeed sound implausible. Pure gold is very weakly diamagnetic, too weak to have any noticeable effect on an ordinary compass. Some iron impurities in the gold could make it weakly paramagnetic, but I doubt that could be strong enough to throw a compass off.
Mike W.
(published on 05/11/2018)