What to do about corroded coins?

[Rochambeau]

Hey all, brand new here... I recently unearthed 10 pounds of Morgan dollars, a few quarters, and some dimes, all dated from 1878 to 1915 or so. The coins were buried about 2 feet deep in a large glass jar with a wire cage to pin down the lid. I'm pretty certain the jar was already broken by the time my shovel found it, but I pulled out about 200 coins. I have a couple of questions...

The original owner of the property where these coins were found owned the property from 1895 to 1941. He was a boat captain (I have photographs of him and his registration card from the local marina) and I suspect he buried some of his money on his property. The next door neighbor has been here since the mid 50s and told me the kids that lived here after the captain found a double eagle under one of the trees in the back yard. I think there is a reasonable chance there are more buried jars. I'm looking for recommendations on a metal detector that will scan a couple of feet down.

Every single one of the coins has pretty heavy green corrosion and a few have dark purple corrosion. Pictures attached. I took a couple of the coins to a dealer and they told me the coins have been obviously cleaned and are only worth their melt value. It's certainly not true. I gently rinsed the coins in warm water to get the dirt off them and have them sitting in a jar. Many of the coins are stuck together. Is there any way to remove the corrosion without damaging the value of the coins?

Thanks for your advice!

 

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[Red_desert]

Nice cache! I would say go see if any more jars can be found. Then sort through all the comments for best advice. The very fact, coin dealer accused you of cleaning them... maybe a clue the coins are better if left tarnished?

 

[Hunter1805]

First off this is what I would expect to see of coins buried for 80 years in a glass jar. Nice find these look great and you can clean them up just buy soaking in hot water then spraying very hot water on them at the end of the drying cycle and pat dry using a very soft cloth. DO NOT WIPE THE COINS .. There some coin dips that can be used under the supervision of a coin dealer familiar with the dip solutions. Only certain coins can be dipped. If you are willing just lay the coins flat and take a picture of both sides this way rare coins can be ruled out. If you are lucky enough to have a valuable coin, it can be sent out to be professionally "conserved" and graded. I would love to see a list of coins with dates and mint marks you could have a few rare ones in the group .. DO NOT WIPE THE COINS

 

[RJGMC]

Just gotta say, A dealer offering only melt value is just trying to buy low and sell high. It is a very common business practice.
Don't fall for it, pretty sure you can realize more than that for such a nice cache of coins. Do not be in a hurry to sell them. Nice find! Good luck! Bob

 

[Gare]

First off Let me welcome you to Treasurenet.com
2nd. CONGRATULATIONS of your FANTASTIC FIND !!!1
It would be nice to hear more of your story
3rd if you want to send the coins to me for cleaning NO RETURN ADDRESS NEEDED LOL J/K
I personally know and have hunted with Hunter1805 I know he is VERY KNOWLEDGEABLE
I do NOT KNOW Red_Desert or RJGMC BUT what they say makes sense ALSO !!!!
What ever you do get more then just one DEALERS opinion 1!1!

Gary

 

[Back-of-the-boat]

This is just a suggestion but it almost looks more like a green wax, I would heat up a needle and touch the green and purple spots it might melt off it doesn't look like corrosion usually silver comes out looking good.

 

[pepperj]

WOW! Congratulations on the recovery
When I read the first line I was thinking-oh hear we go again-type post.
Though as I read on then the photos finally popped up it was a tingly shiver-no lie.

The cleaning process can be obtain by various ways and caution should be of key dates in the hoard.
Some have used a solution and low heat (like a cup warmer) over a period of time.

Just read up on the pros/cons of each thing that is suggested.
As far as the vender stating melt value-at least you know the bottom-it's all up from there.

Query: How was this jar found, just by digging or using a detector?

Many upper end detectors will detect a mass of this size at 2 feet. Minelabs, Deus, Garrett

 

[Hunter1805]

Here : This should work but be carful >>>
From JOEFRO/PCGS Message Board

This may be pointless to most of us, but I thought I would share the following experiences with you. At work, I use liquid nitrogen for a variety of cooling purposes and have basically unlimited access to it. Now I know that everyone is against "cleaning" coins because of the long term adverse effects associated with chemical residue and such. However, most people agree that soaking a coin in mineral water to remove "gunk" is an accepted method of non-abrasive cleaning. However, I have read and has personal experiences where some soakings can take over a month to remove dirt and other debris.

LN2 being inert, I conducted the following experiments at work the other day with some pretty nasty coins I had laying around. I soaked the coins in the LN2 bath for about 3 minutes or so until the liquid actually wet the surface of the coin (to assure a minimum surface temperature had been reached). The coins were quickly transferred into a warm/hot water bath. The massive delta T caused a sudden thermal expansion of the gunk and debris stuck to the coin (significantly different from the thermal expansion of the coin's metal), causing much of it to crack and flake off! The great thing about this is that LN2 is completely inert so it does not chemically affect the coins whatsoever, it is purely a thermal expansion effect that is causing debris to come off the coin. Therefore this won't work at all for cleaning off natural patina (definitely a good thing) as LN2 has even less solvent properties than plain water. It is only good for removing gunk and green grime that is often found on old coins in what appears to be a completely non-abrasive and non-harmful method.

I am curious if anyone else around here has tried cleaning coins using a similar method. I sure have never read anything about this before and am curious if it has been explored. 3 minutes in LN2 sure beats a month in mineral water, if you have access.

 

[ironhorse]

Wow!
Ten pounds of silver!!.
...another introductory story of a 'huge ' find, this site never ceases to amaze in what people are still digging out of the ground.
Sadly corrosion on the surface of a coin makes it a 'details' coin and more or less takes away a lot of market acceptance, unless you have some key date and mintmark combinations or some examples of scarce or key dates then the coins are desirable but outside that melt price for corroded coins might be the your only recourse. I dont feel there will be too many collectors who will seek out corroded or even cleaned coins, at least in my experience.
Damage is still damage on a coin whether or not its corrosion or cleaning and there are not many ways turning damage back in to market acceptability unfortunately.
Ten pounds of silver coin still might net you $3k...still not bad for a detecting find!

 

[CreakyDigger]

Wowza! Welcome to TNet from upstate NY....that is one stellar find!

 

[Red_desert]

Just a thought, I can remember reading a treasure legend Washington state, mouth of Columbia River. Boat captain was supposed to have buried caches of coins salvaged from shipwrecks.

Maybe your cache was the only stash he buried or there could be a lot more.

 

[Rochambeau]

WOW! Congratulations on the recovery
When I read the first line I was thinking-oh hear we go again-type post.
Though as I read on then the photos finally popped up it was a tingly shiver-no lie.

The cleaning process can be obtain by various ways and caution should be of key dates in the hoard.
Some have used a solution and low heat (like a cup warmer) over a period of time.

Just read up on the pros/cons of each thing that is suggested.
As far as the vender stating melt value-at least you know the bottom-it's all up from there.

Query: How was this jar found, just by digging or using a detector?

Many upper end detectors will detect a mass of this size at 2 feet. Minelabs, Deus, Garrett

I was digging a footer for some stairs when I heard the sound of breaking glass. When I pulled my shovel up from the hole, I could see silver coins. I knew instantly what I had found.

Some time later, I rented a cheapo detector and scanned around the yard, but only found a few bits of junk no deeper than 4-5 inches.

 

[Rochambeau]

I use liquid nitrogen

If only I had some of that lying around . But I appreciate the thermal expansion concept. Thanks for the follow up.

 

[Rochambeau]

Wow!
Ten pounds of silver!!.
...another introductory story of a 'huge ' find, this site never ceases to amaze in what people are still digging out of the ground.
Sadly corrosion on the surface of a coin makes it a 'details' coin and more or less takes away a lot of market acceptance, unless you have some key date and mintmark combinations or some examples of scarce or key dates then the coins are desirable but outside that melt price for corroded coins might be the your only recourse. I dont feel there will be too many collectors who will seek out corroded or even cleaned coins, at least in my experience.
Damage is still damage on a coin whether or not its corrosion or cleaning and there are not many ways turning damage back in to market acceptability unfortunately.
Ten pounds of silver coin still might net you $3k...still not bad for a detecting find!

Given that I know for certain the property was originally owned by a Captain, and that it is very likely that he was the one to bury the silver, I'm like one step removed from finding buried pirate treasure. For all I know, he could have been running Canadian Whiskey down from BC to Seattle during Prohibition... Seems a shame to sell the silver for melt. Maybe it will be useful when the apocalypse comes...

 

[pepperj]

Given that I know for certain the property was originally owned by a Captain, and that it is very likely that he was the one to bury the silver, I'm like one step removed from finding buried pirate treasure. For all I know, he could have been running Canadian Whiskey down from BC to Seattle during Prohibition... Seems a shame to sell the silver for melt. Maybe it will be useful when the apocalypse comes...

Keeping the silver for a rainy day is a easy as you didn't take the capital to buy the 10lbs to begin with.
Thanks for the reply on how you came across the hoard.
The rental dept. detectors are not going to obtain the depth you probably need.
Another option is to look for a dealer that has a higher end used machine that would rent/lease to you to offset their investment.
Best of luck hope something more show up for you.

 

[Red_desert]

I was digging a footer for some stairs when I heard the sound of breaking glass. When I pulled my shovel up from the hole, I could see silver coins. I knew instantly what I had found.

Another TNet member, once found at least 2 jars of silver coins, digging for a drain tile in the yard 4 ft down.

 

[Red_desert]

Given that I know for certain the property was originally owned by a Captain, and that it is very likely that he was the one to bury the silver, I'm like one step removed from finding buried pirate treasure. For all I know, he could have been running Canadian Whiskey down from BC to Seattle during Prohibition... Seems a shame to sell the silver for melt. Maybe it will be useful when the apocalypse comes...
You live on the west coast? I know another TNet member, lives in Seattle who does have equipment both land and water (has a boat also).

 

[CreakyDigger]

You might try posting this in Today's Finds with a headline like, "I found 10 pounds of silver coins in a Mason jar." Get a lot more hits, votes.

 

[Treasure_Hunter]

Just FYI, the larger the metal mass the deeper a detector will see it. While a single large coin may be seen at say 12-14 inches with detector A, a 10 pound can or jar of silver is a large metal mass and would be seen by the same detector at a much deeper range say 2-3 feet.

 

[UnderMiner]

I've seen this green corrosion before, it is merely the oxidation leaching out from the 10% copper within the coins. I believe it is water soluble and should easily come off in hot water.