The colors of copper Public Deposited
- From johnmenc@optonline.net Wed Apr 03 06:30:34 2013
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Date: Wed, 03 Apr 2013 13:30:31 -0000
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From: "colonialjohn" <johnmenc@optonline.net>
Subject: The colors of copper
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For those attending the EAC XRF talk this bit of information may help prior=
to this discusssion. When we think of copper corrosion on our coins we gen=
erally think of "green color." Copper corrosion can take on various colors =
- so here is a typical suite of colors:
1. Cuprite (Cu2O)=3D Red-brown color.
2. Atacamite (Cu2(OH)3Cl) =3D Yellow-green
3. Malachite (Cu2(OH)2CO3) =3D Green
4. Chalcocite ((Cu2S) =3D Dark Brown to Black
5. Brochantite CuSO4=B73Cu(OH)2 =3D Green to bluish green
Normally you start with Cu2O and then atacamite and brochantite normally fo=
llow if the corrosion progresses further along ... so we normally see green=
/red to brown to black (final state).
Phil - the best paper I have seen on this subject involving a billon alloy:
http://link.springer.com/article/10.1134%2FS2070205110061012#page-1
JPL
--- In colonial-coins@yahoogroups.com, "colonialjohn" <johnmenc@...> wrote:
>
> Mark Fashian & XRF ... tempting ... I am sure there will be alloy differe=
nces between a 1794 Starred Reverse (S-48) and a 20thC Lincoln Cent ...
>=20
> --- In colonial-coins@yahoogroups.com, Ray Williams <njraywms@> wrote:
> >
> > Hi Guys!
> > On our C4 website is information about the upcoming EAC=20
> > Convention. A direct link to it is:
> >=20
> > http://www.colonialcoins.org/upcoming_meetings_and_events.htm
> > Ray
> >
> - 2013-04-03
- 1
