Shipwreck Gold: Would it have slabbed if it were not from a famous shipwreck?
Would it have slabbed if it were not from a famous shipwreck? This question was asked of me after posting an image of a double eagle recovered from the SS Republic on a NGC message board. Link to post
At the 2000 ANA World's Fair of Money in Philadelphia, Bob Evans, Chief Scientist and Curator of the SS Central America treasure, had just finished giving a presentation on the SS Central America when a gentleman asked, "Why do these coins get graded when coins from other shipwrecks get returned as no grades?"
So the question is not new to the SS Republic shipwreck. As far as Type 1 Double Eagles (1850-1866) are concerned, it also applies to the SS Yankee Blade, SS Brother Jonathan, and SS Central America shipwrecks. Why do gold coins from the SS Yankee Blade get returned as no grades when most of the coins from the other three wrecks get graded?
As Bob Evans answered at the presentation in 2000, "the coins speak for themselves." My understanding is that the coins really get put into two groups, those that are "numismatic" and those that show a "shipwreck effect". In other words, numismatic coins show no signs of having come from a shipwreck. The shipwreck effect coins, on the other hand, show signs of having been in a shipwreck.
Gold coins from the SS Central America, SS Brother Jonathan, and SS Republic were mostly graded while, as far as I know, no gold coin from the SS Yankee Blade has been graded and attributed to the shipwreck. The reason is that SS Yankee Blade coins show salt water effect in the form of cracks on the surface of the coin. So this is one shipwreck that is missing from my collection. (see The Arlington Collection of Shipwreck Gold )
So the answer to the question is that the gold coins (this does not include the silver) from the SS Central America, SS Brother Jonathan, and SS Republic shipwrecks, if looked at raw, could not be distinguished from a similar non-shipwreck coin and therefore they get graded.
The reason for this is most likely due to the underwater environment of the shipwrecks. Although gold is a soft metal, it is virtually indestructable and chemically inert. Basically, that means that few things will react with gold in a harmful way.
However, one of the chemicals that does react with gold is chlorine. Chlorine causes gold to corrode under acidic conditions. Seawater is loaded with chlorine. So the key to the condition of the coins is the level of acidity at the site.
My understanding is that shallower seawater sites, with a mostly sand or silica seabed, have a highly acidic environment. This acidic environment, combined with a more turbulent environment, causes damage to the gold coins in the form of corrosion and/or "sandblasting" from the surrounding sand. This apparently was the case with the SS Yankee Blade and other shallow water shipwrecks in the past.
With the deep water shipwrecks, the surrounding environment is not one of silica, but one of calcium carbonate, also known as lime. Apparently, this is a result of thousands of years of shells falling and settling on the bottom of the ocean. This is an alkaline substance that would counter acidic conditions. So the coins resting in these deep water shipwrecks were preserved instead of corroded.
Unfortunately, the same can't be said for silver coins. The silver coins from the SS Central America and SS Republic that I have owned were all not graded. All of them showed shipwreck effect in the form of saltwater etching on the surfaces or corrosion.
In general, shipwreck gold coins are actually in better condition than non-shipwreck coins, especially Mint State coins. If you had unlimited resources and wanted to create a collection of Type 1 Double Eagles that were all the finest known or even condition census for each date and mint, you would have no choice but to include coins from these shipwrecks. 1857-S coins have been graded as high as MS67 by PCGS! As for the SS Republic, an 1865 Philadelphia graded MS66* (star designation) by NGC!
Here is a picture of one of the shipwreck coins that I own. You be the judge!
Click to Enlarge
Treasure Ship: The Legend And Legacy of the S.S. Brother Jonathan
Lost Gold of the Republic: The Remarkable Quest for the Greatest Shipwreck Treasure of the Civil War Era
Ship of Gold in the Deep Blue Sea
The treasure ship S.S. Brother Jonathan: Her life and loss, 1850-1865
America's Lost Treasure
Agony and Death on a Gold Rush Steamer: The Disastrous Sinking of the Side-Wheeler Yankee Blade