At 11:36 PM 11/12/2006, you wrote:
>I have heard quarters are mostly copper ?


The dime, quarter, and half dollar are all 91.6%=20
copper and the rest nickle.  See:
http://www.usmint.gov/about_the_mint/index.cfm?action=3Dcoin_specifications

The weight of each is in direct proportion to it's face value, so if used=
 for
damping, the half dollar might be the best choice.


Although Cu is slightly repelled by a magnet, the=20
Cu Ni alloy will be slightly attracted.
However, this attraction might be small enough to ignore.

http://prola.aps.org/abstract/PR/v38/i4/p828_1
The magnetic susceptibility of alloys of copper=20
and nickel in proportions ranging from 0.1 to 70=20
percent nickel have been studied. X-ray=20
photographs of the alloys show that they are a=20
homogeneous mixture of the copper and nickel=20
crystals. Although copper is only weakly=20
diamagnetic it requires 0.8 or 0.9 percent nickel=20
to neutralize this diamagnetic effect and 56=20
percent nickel is required before the alloy shows=20
ferromagnetic properties at ordinary=20
temperatures. For amounts of nickel from one=20
percent up to 30 percent the alloy, while=20
paramagnetic in most respects, does not obey any=20
known law of paramagnetism with regard to=20
temperature. As the temperature is increased the=20
susceptibility first increases and then=20
decreases, the maximum occurring in the=20
neighborhood of the Curie point for nickel. In=20
the case of alloys containing more than 30=20
percent nickel the susceptibility decreases with=20
increase of temperature for temperatures above 20=B0C.

McMaster Carr  charges=20
$20.84 for a 1/16" strip of Cu, 1 inch wide by 6 inches long.

Maybe flattening a piece of Cu pipe is still the=20
best way to go.   Have to be sure it's copper and=20
not brass=20
pipe.  See:=20
http://www.copper.org/applications/plumbing/techref/tpf_stds/tube_pipe_stds.=
htm

Cheers,
John =20


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