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 Replies: 19 / Views: 3,708 |
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Valued Member
United States
211 Posts |
All coins tone eventually.
The speed with which a coin tones will depend on:
-The metal of the coin
-The metal impurities in the coin
-The physical surface properties of the coin
-The temperature the coin is kept in
-The moisture content of the air the coin is kept in
-The chemical impurities of the air its stored in
-The age of the coin
-Light exposure
-The material the coin is stored in
As you can imagine, toning can get very complicated very quickly. A complete understanding of toning can even challenge the understanding of a trained chemist.
Generally keeping coins in a cool, dark, and dry space will be all you need to keep coins from toning more than a normal amount. The sky is the limit for how much you want to get into it and study it.
Edited by JimmyJames
02/13/2017 6:49 pm
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Moderator
 Australia
16850 Posts |
Coins are made up of one or more metallic elements. Bright shiny metal is not the natural state those elements occur in on the surface of the Earth. So, from the moment a coin is struck, the metal the coin is made of is trying as hard as it can to turn back into the metallic ore from whence it originally came. Depending on the circumstances and on whether or not we wish this to happen, we give this process various names: oxidation, toning, tarnish, rust, corrosion... all different names for much the same chemical processes.
Gold is, of course, the notable exception. Pure gold will not corrode under normal atmospheric conditions. "Coinage gold" - gold that is alloyed up to 10% with other metals, such as copper - can oxidize or tone slightly, thanks to the presence of the contaminating elements. But a pure or essentially pure (above 98%) gold coin will still look just as mint-fresh and shiny as it does today, even if you bury it in the ground and dig it up again in a couple of million years.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
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Bedrock of the Community
United States
20753 Posts |
These will never tone:   Quote:
Pure gold will not corrode under normal atmospheric conditions. However, this sort of depends on a few things. For example Gold will not only tarnish but does combine with Chlorine. Also, Fluorine and Cyanide. Where these are present in quantities, it does effect Gold and I will tarnish. Sulfur to some extent also effects Gold to form a Discoloration known as Au2S. And Gold dissolves in Mercury. |
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CCF Advertiser
United States
1533 Posts |
Gold coins contain copper, so acquire an orange hue.
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Bedrock of the Community
Australia
21788 Posts |
I have seen brilliant red coins Mint state over 100 years old. (Indian 1/4 Anna)
I think that almost all of the tarnishing rate is due to the environment in which the coins have been kept.
Tone = beautiful, tarnish = ugly. All is in the eye of the beholder. Chemically, they are exactly the same thing.
The word 'patina' is usually applied to fully and completely toned coins. Such a patina can actually protect the coin. Nevertheless, such complete toning into a patina is still a form of surface corrosion.
Don't knock back a blast white uncleaned MS Morgan!
PCGS Photograde will show you why.
Edited by sel_69l
02/15/2017 04:47 am
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Bedrock of the Community
United States
17884 Posts |
Quote:
However, this sort of depends on a few things. For example Gold will not only tarnish but does combine with Chlorine. Also, Fluorine and Cyanide. Where these are present in quantities, it does effect Gold and I will tarnish. Sulfur to some extent also effects Gold to form a Discoloration known as Au2S. And Gold dissolves in Mercury. While these are all true, normal atmospheric conditions do not normally contain a lot of Chlorine, Florine, or Mercury and usually not a lot of sulfur unless you are downwind of a lot of decomposing organic matter or an active volcano. You WILL find very tiny amounts of Chlorine , Mercury and hydrogen sulfide in the normal atmosphere (almost never Florine, it's too reactive), but the quantities are so small that the chance of them toning your pure gold coins is negligible even over millennia. Edited by Conder101
02/15/2017 1:51 pm
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Bedrock of the Community
United States
20753 Posts |
Quote:
and usually not a lot of sulfur unless you are downwind of a lot of decomposing organic matter or an active volcano. Not so. Many Fossil fuel power stations burn Sulfur rich coal. The fumes given off are either SO or SO2 pending the temperature of the burning and the amount of Oxygen. Lately many of them have gone to DeSulfurazation systems that remove large amounts of Sulfur but turns it into SO3 in HOH or H2SO3 known as a weak acid. The further neutralization is rather expensive so many power stations just don't do that. I've worked in the Engineering of many power stations where Sulfur in the ground in those places is extensive. Also, in some areas that used to have what is known as open pit smelters for Steel, like in Indiana's Gary Works area, Sulfur rich grounds are common. I used to come home from those places smelling like a rotten egg. |
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Moderator
United States
189340 Posts |
Quote:
Also, in some areas that used to have what is known as open pit smelters for Steel, like in Indiana's Gary Works area, Sulfur rich grounds are common. I used to come home from those places smelling like a rotten egg. Way back in the day, some of my family worked for Inland Steel in East Chicago. I could tell when they got home by smell before I would see or hear them.  |
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Valued Member
United States
99 Posts |
Here are 2 toned coins. The one on the left is one I was playing around with artificial toning. the one on the right I bought and was in the paper envelope for 30 years. The sulfur in the envelope caused the one on the right  |
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Valued Member
Canada
249 Posts |
Please send me the envelope, that coin is gorgeous! Maybe, given time, I can replicate the result.
You might be a little off on your 30 year estimate though.
The date on the coin is 1996.
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Bedrock of the Community
United States
20753 Posts |
Quote:
You might be a little off on your 30 year estimate though.
The date on the coin is 1996. He ment on the Planet Venus. Years are shorter there so his 1996 coin could have gone for even longer than 30 years.   |
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Valued Member
United States
99 Posts |
Ha... and they say nothing wrong with our educational system
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Valued Member
United States
99 Posts |
I never looked at unill about 6 monthe ago. I was a little surprised at the toning. Bought it brand new from a little bank in Pendleton,OR. That was the envelope he gave me.
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Valued Member
Canada
249 Posts |
jim7219, you should post pictures of your 1996 coin on the Eye Candy Corner forum for all to enjoy. Is the obverse just as nice?
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Valued Member
United States
99 Posts |
Yes it is. One side does have part of a finger print though. I will post it there.
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Replies: 19 / Views: 3,708 |
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Posted 02/14/2017 01:17 am
