To bury, or not to bury: Coins of Saddle Ridge Hoard among the vast number hidden underground for 'protective' purposes

Preserving Collectibles column from June 30, 2014, issue of Coin World
By , Special to Coin World
Published : 06/12/14
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The 2013 discovery in California of the Saddle Ridge Hoard of U.S. gold coins reflects people’s penchant for hiding, burying or otherwise concealing their coin collections. This is by no means new. Periodic discoveries of caches of coins on archaeological sites in Israel, Greece, and England show that the practice of burying coins to protect them from theft has gone on for millennia.

I recently received an email from a longtime reader:

“A friend is considering burying some of his coin collection in his backyard. Although he has a safety deposit box, he fears that the government could confiscate his collection at some point down the road as President Roosevelt did in 1933. He said he will use an air-tight, water-proof box. Is this really a good idea?”

The short answer is no. I cannot think of a more harmful and inhospitable environment for housing coins than to bury them underground. Essentially you are creating an archaeological site in your backyard and turning your coins into artifacts. The burial environment is harsh and little of what is buried actually survives.

If an object does survive, its condition will not be the same as when it was buried. Burying a coin subjects it to a wide variety of environmental factors that can affect its stability and survival.

The rate at which a buried coin degrades depends on the type of soil, its porosity, pH and salinity. The metal or alloy of a coin is also important. The main reason the Saddle Ridge Hoard coins survived burial so well is that they are gold.

Gold is a noble metal and, as such, corrosion resistant. You will note that the tin cans that held the coins are corroded. Tin cans are made from steel that is coated with a thin layer of tin. The tin provides a physical barrier, protecting the steel from corrosion. Once this layer is compromised, the underlying steel will corrode.

Also consider that putting gold coins in a tin can sets up a corrosion cell. When dissimilar metals are in direct contact, the baser metal will corrode preferentially.

Even if the reader’s friend does manage to create a water-tight, burial-resistant container, a risk of condensation forming inside exists when the temperature outside drops. He should also consider flooding, earthquakes, frost heave, burrowing rodents, and neighborhood dogs. Finally, there is the issue of retrieval. Will he remember where he buried the coins? Will he share the location with his family? All are important considerations.

On a completely different note, I will be participating in the Coin Grading and Preservation Workshop Aug. 12 in Mississauga, west of Toronto, at the Royal Canadian Numismatic Association show.

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