Written by the TreasureGuide for the exclusive use of treasurebeachesreport.blogspot.com.
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| Heavily Corroded Carolus Bust Coin From Wreck of the Sand Pedro Alcantara. Source: See the researchgate.net link below. |
I found a good study of the corrosion of silver coins from the wreck of the Sand Pedro Alcantara, which sunk in 1786.
Here is the abstract.
A detailed morphological study of the corroded surfaces of seven silver “Pieces of Eight” recovered from the San Pedro de Alcantara shipwreck site was conducted using low pressure scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) analysis. Mosaics of the backscattered images of the coin faces indicated that the coins consist of a solid solution of β-phase grains with α-phase inclusion and that bromian chlorargyrite is the main corrosion product. Thin surface films of hydrated iron oxides facilitated the formation of sulphide minerals on buried coins. Surfaces were heavily abraded by the harsh erosion corrosion conditions and most bear evidence of damage from impact of other artefacts on-site. Correlations exist between the surface analyses and the data from the in-situ corrosion measurements.
And here is an excerpt describing the coins that were studied.
The initial in-situ corrosion studies of silver coins focused on seven coins that represented varied geographic locations, which were subsequently recovered and these objects formed the locus of this study. The pieces of eight (8 reales) were minted in Lima, Peru, and showed a “bust type” portrait of Carolus III on the obverse and the Spanish coat-of-arms on the reverse (Figure 1). They were minted between 1772 to 1788 when the King was succeeded by his son Carolus IV. The coins had mint dates of 1780 (no 4030), 1784 (no 4324) and 1782 for numbers 4327, 4331 and 4342 while 4315 and 4325 were too heavily abraded and could not be dated...
As you might expect, the degree of preservation of the recovered coins related to their location on the wreck site
Some were found buried under 15cm of coarse sediment. Those mostly retained their original dimensions.
Some of the coins were found lying atop the seabed. They had lost the majority of their original surface and dimensions.
Only one of the coins that were studied showed a significant amount of concretion. The concretion consisted of sand-sized to pebble-sized sedimentary particles and small shells bound together by calcareous concretion.
Some of the coins had considerable amounts of iron corrosion products on their surfaces. Iron in some cases preserved coin details in a couple of ways.
Here is the link for that article, which includes many more details.
If you can use the appearance of a coin to figure out where it has been you know where to look for more.
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| End of World War II. |
There are times in life that standout and you'll likely never forget. My mother, of course, never forgot D-day and many of the events of World War II.
In one recent post I mentioned the Thanksgiving Storm of 1984 and also the 2004 season that brought us Frances and Jeanne. It was twenty years between them. They were very different in some ways, but they are connected in metal detecting history as times that will long be remembered.
Hunting conditions like that don't happen very often. It might seem like yesterday, but sixteen years have passed since Frances and Jeanne hit the Treasure Coast, and thirty six years have passed since the legendary Thanksgiving Storm. There are very few detectorists still around that worked the beaches after the Thanksgiving Storm, but more that were here for Frances and Jeanne.
Those kinds of exceptional times happen infrequently. Those kinds of circumstances present an unusual opportunity, which can benefit anyone - young or old - skillful or less so. It takes a bit of luck just to be there. During such times, great discoveries can also be made by the complete novice.
One of the problems with lucking into a big find beyond your skill level is the hope and expectation of matching or exceeding it. You don't want to be talking about the big find you made 16, 20 or 40 years ago for the rest of your life. Some who make an good find too early, such as the lady that found a gold Spanish shipwreck coin on her very first outing, give up before long because it is so difficult for a beginner to come anywhere close to matching the excitement of such a nice find.
One thing that makes events like the Thanksgiving Storm and 2004 so special, besides the rarity, is the number of people that get to participate in the excitement and the stories that are shared later.
If you have been detecting for a good while and think back, there are probably times that you will always remember. Maybe they won't go down in metal detecting history, but you will never forget them because they were special to you.
As I think back there were times when it seemed that Davey Jones' locker suddenly opened up. And there were days when conditions were poor, but I got a surprise and made a special find anyhow.
Special finds are not always the most valuable finds. Sometimes they are special in other ways. A find might be special because it was special to someone else. Maybe you were able to return a wedding ring or memento of a deceased loved one. Those things can be just as memorable as some trinket that you will store away and someday maybe sell. I'm not much impressed by those kinds of things anymore.
In fact a couple of my most memorable metal detecting days had nothing to do with finds at all. One day I was standing in shallow water all by myself in a dense fog and could only see a few feet around me in every direction. The water was a still as glass. It was so calm and wonderful. I can't describe it, but it was an awesome sight and feeling. I just wish I had been able to record it somehow.
As time goes by I know I'm getting less clear on some events. And I didn't always record things like I should. Every once in a while I do an internet search for some bit of information search and end up being linked back to an old post in my own blog. And maybe that is one reason I do this. I remember information and events better when I take the time to write it down and share it.
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| Two Areas To Watch. Source: nhc.noaa.gov |
There are two areas to watch for the next few days.
Happy hunting,
TreasureGuide@comcast.net