Copper coins- More likely than silver to Corrode?

taxbuster1040

If I am interested in buying 19th century copper, do I have to be more concerned than if i aquire 19th century silver coinage, that the copper will pick up corrosion if I am placing the coins in a safe deposit box? I recently had Anacs grade an indian head penny, that came back marked corroded on it. For the life of me I could not see corrosion. WHile on the topic, does copper corrosion indicate itself by a green fuzz on the coin, or can corrosion look like something else?

TomB

It's unlikely that you will get much, if any, corrosion on coins simply from being stored in a bank safe deposit box. Copper is more reactive than silver and it will corrode much more quickly than silver. Copper damage can be bright green as in verdigris or can also be bright red. If your coin was labeled as corroded it might have had corrosion removed from it, therefore, there may be no evidence of active corrosion on the coin but the damage left behind was the reason for the label.

carl

Lot of that depends on where you live. Copper reacts excessively with sulfurus or sulfuric acids. In areas such as the Gary works in Indiana the air is still kind of full of sulfur from contaminated grounds and buildings although most of the steel mills are now gone. Many of the mills there used what was know as open hearth funaces which contaminated the air with Sulfur Oxides. Sulfur Oxide mixes with moisture in the air to create the acids that cause the green discolorations to copper, forming CuSO3 or 4. Silver on the other hand more readily reacts with nitrates and is less likely to form AgSO3 or 4. If silver has some contact with fertilizerts that contain nitrates, they may be greatly effected forming AgNO types. Save deposit boxes are not air proof so if minute traces of such air contaminates are present in your area your coin could slowly become effected. For instance many people in the Gary area have had numerous problems with copper piping falling apart in their homes from acid air and statues are disintigrating due to acid rain. Many of the copper pipes in homes around my area have small traces of this so people coat their pipes with plastics. I've got most of my valuable coins in albums rapped in plastic bags and sealed with an iron in a bank safe deposit box. Coins I've had for 40 to 50 years show no sign of contamination at all. Again, as to which will corrode faster, it all depends on where you live, how you store them, what is near by, how you handle them, etc. The best thing to do is to collect everything, wait a few hundred years and give us your results.

taxbuster1040

Thanks for the info, guys......

Conder101

Silver will react vey readily with hydrogen sulfide though to create silver sulfide. And hydrogen sulfide is very common in trace amounts in the air just aout everywhere. Some major sources of hydrogen sulfide are decaying organic matter, car exhaust, flatulance, cooking with naural gas, and power plant emissions.