ON DATING ARCHAEOLOGICAL SITES USING COINS

"A hiker in southern Utah has found what appear to be old Spanish coins possibly dating back to the time of the conquistadors and perhaps even earlier, long before the voyages of Columbus."

There are some gaps here as many readers have already noted. Suspicion abounds regarding the unidentified tourist who found two Spanish copper coins. So far, there is not much journalistic detective work going on. First of all, just exactly where and how did this hiker find these coins? The park management is not talking, so far. And who is the hiker?

The Spanish 16 maravedis coin from the 1600s could have come from Spain in the pocket of some explorer centuries ago - but that is highly unlikely. The medieval dinero burguese the smallest denomination from King Alfonso X's reign in Castilla y Leon of about 1280 is another story. No way it could have been loose change even here in Spain in the 1600s. Too many governments and monetary systems have been in use since it was issued. Both coins appear to have been buried long ago and since been in a protected environment. That's a clue to what has occurred here.

Exactly where were these coins found? By that I mean were they in a dry cave? It does not seem like they could have spent decades out in the wild open countryside. Some clues: The coins have not been exposed to much weather in recent years, in my opinion. The numismatic value of the two coins is perhaps $30. Both coins appear to be genuine - either is a type worth faking. The low numismatic value makes tomfoolery more likely, however. As was already suggested, the idea of a bit of historical horseplay is quite possible here. Because I am a serious numismatist but also a recovering smart-ass, I know it would be great fun to pull tricks on people with old coins.

I would like to focus my comments and questions on coin damage created by burial or being hidden away in some manner. Patina tells us a lot about what a coin has been doing as the decades roll by. I am no specialist on coin corrosion but the topic is interesting. This quick report poses more questions than answers.

CASE STUDY
This copper coin strip shows how burial in dirt can wreck rare items. Here are photos of each side - one worse than the other. This Segovia roller dies mint strip was created in 1662 and tossed into the weeds along with many others by mint workers. It was underground from then until 2014 when archaeologists excavated the dirt near the mint. They missed finding this piece, but with the help of my metal detector I found it. I followed the dump trucks to the land fill where the abandoned dirt was piled. This curved strip is an example of one side of the coin being heavily corroded and the other side less harmed. Which side was up and which was down I leave to a specialist, but after 352 years in ground which received rain and snow every year, the difference in damage is dramatic.

CASE STUDY
Here is a coin I found a few years ago in dirt from the basement of an old church. It was somehow dropped onto the dirt floor of the basement in 1827 when uncirculated. So it was on dirt but under a roof. It is possible it was not buried in dirt. But if it was it was consistently dry dirt. Whatever the exact situation over 187 years, the result, Unc patina still there but copper cancer appearing in spots.

Here is the coin getting a vertigris removal treatment. Alas, the bits of shinny original patina were lost in further processing, but they copper cancer was stopped. You can see that the coin has no wear whatsoever, even as the luster was lost.

I would guess than the coin was face down in the dirt because the vertigris is worse on that side. The reverse had only a bit of corrosion on the upper area and it

The silver wire brush treatment previously lasted only a year or so.

NOTE: I sent in photos and info on this coin a few years ago.

CASE STUDY
Here are photos of two small hoards of coins that spent more than 1,000 years in a pottery pot. Ideally, this would have been a dry environment with air around some of the coins.

This pottery jug held a small hoard of silver coins in Scotland

This pot held silver coins in Spain

CASE STUDY
These Roman silver coins minted at one of its German colonies were hidden away it such a way that the absolutely uncirculated nature of the pieces were perfectly preserved. These no doubt were cleaned by museum specialists but you can see flawless beauty in the coins.

There are those who criticize some of the cleaning treatments archeologists do on coins. But in this case we see exactly how those coins looked just as they were struck for more than 1600 years ago. No harm done.

CASE STUDY
There is nothing worse to ruin silver coins than salt water. This shipwreck 8 reales piece really got chewed on over three centuries.

CASE STUDY
This gold cob was one of dozens that went down with a galleon off the coast of Florida and spent 300 years in salt water and sand. But thanks to the nature of gold, that insult goes completely unseen. We could say that gold coins simply do not apply to this corrosion study.

A wild idea:

Someone could assemble a photo collection of example coins showing how various situations cause patina, tarnish and oxidation. (Tarnish being patina we don't like) This could include examples such as:

• Silver coin buried with others in a pottery pot for 500 years
• Silver coin buried with others in a copper pot for 500 years
• Copper coin buried with others in a pottery pot for 500 years
• Copper coin buried with others in a copper pot for 500 years

• Silver coin buried with others in a pottery pot for 100 years
• Silver coin buried with others in a copper pot for 100 years
• Copper coin buried with others in a pottery pot for 100 years
• Copper coin buried with others in a copper pot for 100 years

• Silver coin buried in dry dirt for 500 years (desert environment)
• Copper coin buried in dry dirt for 500 years in a cave
• Silver coin buried in occasionally moist dirt for 500 years
• Copper coin buried in occasionally moist dirt for 500 years

• Silver coin kept in a wood cabinet indoors for 100 years
• Copper coin kept a wood cabinet indoors for 100 years
• Silver coin kept in a wood cabinet indoors for 300 years
• Copper coin kept a wood cabinet indoors for 300 years

Well - you get the idea.

To read the earlier E-Sylum articles, see:
UTAH SPANISH COIN FIND PUZZLES PARK SERVICE (https://www.coinbooks.org/v22/esylum_v22n17a23.html)
Mystery of the Spanish coins that predate Christopher Columbus by 200 years and have been found deep in the Utah desert

	NBS (coinbooks.org) Web