please help me with this silver roman coin

Hi,
I was wondering what the green fuzzy spot is on the obverse of this roman tetradrachm of Macrinus from Syria. I've been reading about bronze disease, which is usually green and fuzzy looking. Is it possible that this is bronze disease even if it is a silver coin? I know that these tetradrachms are often debased and may contain bronze or copper. I have attached a scan of it. What do you think it is??? Please help!!!

 

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Certainly looks like corrosion to me. This is one case where I will recommend cleaning. The corosion will damage the coin.

 

EEEK!!! Should I treat it any differently than a bronze or copper coin? That is, because it is silver, would it be OK to use the recommended distilled water?
Also, what are the chances of the disease spreading to other coins in my collection? The coins never physically touch each other, as they are in flips on a plastic page in a 3 ring binder, but I'm not sure if that would stop it as they are still side by side. PLEASE RESPOND AND HELP ME!!!! THIS COULD BE VERY SERIOUS AND DESTROY MY ENTIRE COLLECTION!!!!

 

You will need more than distilled water at this point. Visit your local coin shop and buy some form of coin dip. Use a QTip to gently remove the corrosion. DO NOT rub the coin with a cloth. The less cleaning the better.
Corosion does not jump from coin to coin. After cleaning the coin, rinse it with distilled water, and pat dry. DO NOT rub the coin. Place in a new holder, and all with be right with the world.

 

Thank you!!

 

I agree with National dealer. I am not sure just how much he knows about ancient coins in particular, but his advice makes sense. Yes, you are correct. Many of the tetradrachm coins of that time were of debased silver, referred to as 'billon' silver.

Since there is a relatively high copper content in these coins, they are often found with various degrees of corrosion. National dealer sounds like he is more familar with U.S. and other later coins than with ancients. However, what he said is good advice. But unlike U.S. coins, we can be more liberal in what we do with ancient coins in terms of cleaning them.

You certainly would not want to do anything that would destroy any of its original surface or numismatic value if at all possible. I will tell you that you CAN indeed stop the spreading of the corrosion once you have removed as much of it as possible. You can do what archaeologists do when they find these coins, and that is to put a thin coating of laquer over the coin. This is, of course, up to you. You may not like the idea of doing that and many people do not; but it is an accepted way of preserving ancient coins and is used by archaeologists themselves. You may want to look into this further yourself before trying this. Regards,

John

 

Hello National dealer,

The subject of ancient coins is more of a specialty subject. There are actually a lot of different methods used to clean and preserve ancient coins. Your advice appears to be more related to U.S. or modern coins.

The fact of the matter is that we DO 'rub' ancient coins. In fact, some are so corroded that many collectors use metal wire brushes on them in order to 'clean' them. Ancient coins come in various degrees of condition including extremely corroded and even encrusted states. There have been times when I have had to used a hammer and chisel.

Most local coin shops do not carry supplies for ancient coins. As I had just said above, there are many methods used by collectors of ancient coins to deal with various conditions or states in which these coins may be in. A friend of mine uses lemon juice and water and just soaks coins in that solution for whatever amount of time it takes, then he soaks them in a soap/water solution. And he repeats the process as needed. Once he has a coin as clean as he wants, or intends, he then dries the coin with a cotton cloth and puts a light coating of olive oil on the coin and puts it into a 2x2.

And, as I had pointed out to Yabodo, archaeologists will put a coating of laquer on coins to retard corrosion. This laquer can be removed at a later date with a solvent. And, as any collector of ancient coins knows, corrosion CAN indeed 'jump' from one coin to others. That may depend upon a number of factors including exposure to a damp environment, etc. There is a great deal to learn and know about when it comes to the subject of ancient coins. Thanks for trying to help Yabodo. John

 

JDSCoin,

While I am aware of different methods used for cleaning ancients, I used this particular case for my post. The coin in question doesn't need to be harshly cleaned to remove the corrosion.

 

Hello National dealer,

I understand the advice that you had given in this case. But what I had stated was not to say that the coin in question needs to be harshly cleaned, but to point out that there are many methods and instances involved when it comes to ancient coins. Ancient coins are a whole different animal than modern or later coins.

The issue of cleaning and preserving ancient coins is a huge subject and not one that has one simple answer. And, as I also pointed out, corrosion can and does 'jump' from one ancient coin to another. It does so because the green corrosion can flake off and become air-borne, landing onto other coins. With time and any dampness in the air, it can begin to corrode other coins. This is why we take precautions like putting a thin coating of olive oil onto coins or even (mostly while out in the field) we put a thin coating of laquer on them.

Regards, John

 

Are my coins safe from the infected coins as they are never in direct contact w/ each other, but are still next to each other in the flips? I ask this b/c I have several other bronze coins in my collection which are on the same plastic page as the infected coin. Can it still jump to other coins from inside the flip, or is this physically impossible? I am starting to HATE the bronze coins that are near it them ( I have 3 coins that are probably infected, although they were bought like that!). I am also starting to dislike this hobby b/c of this disease. It has made me very paranoid about my coins, and made collecting really unenjoyable.

 

Hello Yabado,

It seems that you do have a budding interest in ancient coins and that you would enjoy (have enjoyed) collecting them. Remember, a part of this is what you learn along the way. I would not worry about this as you have. Really, with a bit of knowledge, you are quite safe.

As with anything, a bit of precaution can prevent things from becoming unmanagable. Perhaps the fastest, easiest and least costly ways to prevent damage from corrosion from spreading to other coins is to keep them clean, and apply a bit of oil on them so that the air and other contaminants cannot reach the surface of your coins.

It is generally up to the individual collector as to what methods that they want to use on their ancient bronzes and other ancients. But I do recommend taking care of them and not using harsh cleaning methods if at all possible. I am very careful cleaning my ancient coins. Perhaps I will share some of those here as I get the opportunity to do so.

I will start by saying that simply soaking coins in ordinary water overnight can indeed, help clean some corrosion. You may use plain warm to hot water, with or without liquid soap. If you need to do more, you may think about an ultra-sonic cleaner. This is where I generally start when it comes to cleaning my ancient coins. Be sure that you dry them very, very well. Make sure that you do not leave them damp, as that will lead to more corrosion.

I'll actually have to continue this in another reply as I have a bit more to say to you about this. My impression was that you were in this for the long-haul and that you would want to know of several methods that you could use on various coins as their condition warrants, as you had made it clear that you were concerned about more than that one coin.

Regards, Roman

PS: I did read the other suggestion that was posted. And that may be an option, but I did not see any cost posted. That may be an expensive route if you have more than a few coins that you want cleaned and preserved.

 

Hi GDJMSP,

I can't speak for Yabado, but a part of what makes collecting ancient coins (for me anyway) is the pride that one can take in how they have cleaned and preserved their coins. For me and many others, it is not aggravating, it is a challenge which calls upon our knowledge and experience. In short, it is a main part of what we enjoy in this particular area of coin-collecting.

I think that you have made a good suggestion for certain circumstances. However, you never mentioned what the cost would be for this service. Most of the people that I know who collect ancient coins are concerned about expenses as they tend to weigh them against other coins that they might have purchased instead.

Can you give us some idea of what this service costs? Thanks.

John

A little too close to the self promotion rule. ND

 

I've decided to boil the sucker in a distilled water/baking soda solution. From what I've read, that will be the best sollution for bronze disease, and will not destroy or harm the coin. What do you think about this idea?

 

I think this is beginning to sound more like a scene from `Macbeth' (the three witches in particular) rather than a cure for a slight hint of verdigris.

Is there some kind of incantation that goes along with this `remedy' of yours that you are supposed to chant out loud as the coin boils in the chaldron?



Ian

 

If you go to www.ancient-coin-forum.com and go down to coin photography and conservation, there are many posts by very experienced ancient coin collectors that recommend treatments that are more or less similar to what I said. Also, if you go to google.com and type in Bronze disease, there are many different websites that give different cures. After reading most of them, it gets kind of confusing b/c they're all slightly different. It seems the only way to really cure BD is to create a natural chemical solution to counteract it. Baking soda and distilled water, as well as boiling it and also soaking will usually cure it. Heat alone is not enough, and the problem is, there is no one set solution for treatment.
I'm a little ****ed off, as I bought the coins WITH the disease and from the same person. He is the only person I trust to buy ancients from, as he is one of the most reputable dealer around. Now I'm hesitant to buy anything from him again, and he's my only source!

 

I think the crucial factor for any collector is to ensure that they store their valuable coins as well as is possible (ie ones you would feel a tug at the old heart muscle over if they became damaged due to pvc damage or verdigris etc....) . After all it is pretty pointless spending hundreds if not thousands of dollars on coins if the way you are storing them is likely to damage them in any way.

I'm not saying that you aren't storing them properly, but it's worth getting some sound opinion on that score if you are unsure in any way. Many dealers are great at selling you coins but not so great for teaching you what to avoid doing with them once they are yours. That does not make them `bad'........well maybe it does, because I think they have a responsibility to help the collector maintain their collection. Have you spoken with this dealer? I would, if for no other reason than to let them know of the problem you are experiencing and asking for their viewpoint and any advice they can give you. It may not get you much further than you already are but it will provide you with an insight as to how they react to a `customer' who isn't contacting them to `buy', but to call on their `expertise' and good customer relations. ;-)

 

I store my coins the way most ancient coin collectors do: in flips on a plastic slot page in a 3 ring binder. I'm still not sure if flips or cardboard windows are the best storage system, but the dealer I by from uses flips. He's 80 yrs old and has been dealing in coins for about 60 yrs. Unfortunately his hearing is sooo bad, he's pretty well deaf, so it's really hard to talk to him. Although he really knows his stuff, conversation is ltd. to the extreme. As far as I know, I've done nothing to harm my coins (although everytime I hold one in its flip, I always feel like I've damaged it!).
Is my way a good way of storing coins? I'm quite sure I didn't cause it to get bronze disease. I seem to find more coins in my collection that I think have BD, but probably don't. It's getting very hard to tell what is and what isn't diseased. It makes me so upset and depressed, I really don't like even looking at ANY of my coins anymore. It seems this whole thing has really ruined collecting coins for me.
The sad thing is, I still have NO IDEA how to cure it. Since NO ONE can give me a definate answer, I feel very alone on this entire topic.