7/18/18 Report - Old Silver Ring Stolen. Test of Metal Detector On Silver Coins.

Written by the TreasureGuide for the exclusive use of treasurebeachesreport.blogspot.com.

Stolen Ring Thought To Be 1700s Era.

I decided to do a little test using the Garrett Ace 250.  I'll use other detectors in the future, but decided to start with a common and inexpensive model.

For test objects I decided to use coins that were close in size, weight and composition to Spanish reales.  I used a silver dime, quarter, half dollar and peace dollar - all of 90% silver.

The diameters were 17.91, 24.26, 30.6 and 38.1 millimeters, which is close but not exactly like one, two, four and eight reales.  Just as an example, the silver dollar is 38.1 mm and the eight reales would be about 38 mm.  Pretty close.

The weight of the silver coins is 2.59, 6.259, 12.59 and 26.73 grams.  Again, that is close to the weights of the Spanish colonial one, two, four and eight reales, which varied to some extent for a variety of reasons.

The diameters and weights of the coins used in the test are highly correlated.

The vertical scale is diameter in millimeters and the horizontal scale is weight in grams.

The correlation is naturally high, but as you can see the relationship between diameter and weight is not linear.

The similarity of the modern coins and Spanish colonial coins in both size and weight is not accidental - the American coinage being pretty much based upon the Spanish.

I did what I would call a ground test in an area with virtually no mineralization but some amount of ambient electrical interference.

Coins were placed on the ground and the height of the coil that continued to produce a good steady signal was measured.

The dime was detected at approximately 7.5 inches, the quarter at 8.0 inches, the half dollar at about 8.5 inches and the Peace dollar at 9.5 inches.

Depth approximations were not highly precise.  Results were also specific to the location and environment.

Depth detectected relative to coin weight.

Depth detected relative to coin diameter.

Coin weight and diameter are highly correlated, which makes it difficult to tell which is most important, but I have previously found and stated that surface area is more important than the weight of the object in determining how deeply a coin will be detected.  The surface area of the coin, however, is not as important as the presented surface.  By that I mean a coin with a large diameter, if tilted or on edge will not have as large a surface area relative to the position of the coil and therefore will not be detected as deeply.

Given the number of variables and the lack of precise measurements, the results should be taken as only approximations.

All-Metals mode and maximum sensitivity was used during the entire test.

Spanish cobs are all so different that I thought the silver U.S. coins would be more useful as test objects and allow more comparisons and generalizations.  Beach recovered Spanish cobs are all of different sizes and shapes.  As I've reported, they can be less than half the minted weight and are of different shapes.

It should also be noted that the depth was measured when the object was under the center of the detector coil at near optimal sweep speed.  When the object was closer to the edge of the coil, depth was less.  And if a less optimal sweep speed was used, depth would have been less.

I've commented at length on the limitations of both air and ground tests.

In the future I will be conducting more tests with other metal detectors.

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I received an email reporting the above ring stolen during a club meeting.  The owner would like it back.

That, by the way, is another good reason to keep good records on your finds.

Most detectorists go out of their way to return lost items, but like with any group of people, there are some bad apples that spoil it for everybody.

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A lot of people are still reading my old Cooper's Treasure posts.  I don't even watch it.

There is no tropical cyclone in the Atlantic.  The surf is up a foot or two.  The tides are still pretty good, but lessening slightly.

Happy hunting,
TreasureGuide@comcast.net

7/14/16 Report - Shipwreck Graveyard. Where The Boys Were. If You Are An Old Bottle Its Not Always Bad To Look Old. Ace 250 Chinese Knock-Off.

Written by the TreasureGuide for the exclusive use of treasurebeachesreport.blogspot.com.

One of Many Shipwrecks Found Near Fourni.
Source: See link immediately below.

Arcaheologists found 22 shipwrecks in a 13-day survey and 45 in less than a year around Fourni. They range in age from B. C. to 19th century.

Here is the link.

http://www.livescience.com/55375-45-shipwrecks-greek-island-fourni.html

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I just noticed Where The Boys Are playing on TV.  I had to stop and take a look.  It was a little nostalgic.

The movie was made in 1960, and I felt like I was watching a piece of metal detecting history, even though they didn't show any detectorists.  I doubt there were many people that had that reaction, but I did.

They showed the beaches absolutely covered with beach blankets and young people. Did I tell you I used to be young?  It was almost a blanket of people. There was hardly enough room enough to sit or stand.  It was all very civil compared to later years. The girls were wearing one-piece swim suits, and the guys were very clean looking.

In the sixties and seventies the Fort Lauderdale beaches were still very crowded during Spring Break, but things got pretty bad and eventually Fort Lauderdale decided to discourage college kids from visiting at spring break,

I think it was in the mid seventies when they had riots and all kinds of problems.  They brought in Billy Graham to try to calm things down. The beaches were still covered with people at Spring Break into the eighties, as I recall.  How things have changed!

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I just ran across a web site on which the writer was describing how to distress bottles.  They wanted to do crafts with bottles that look old.  What do they say, "The grass is always greener?"  I guess that means the dirt is always dirtier too.

Bottle collectors usually want bottles that look new, and the old bottles I find usually show their age. One thing I like about selling finds is putting them in the hands of the people that appreciate them.  And getting the best price is largely the result of finding the people that most want exactly what you have.

There are bottles that can be sold to bottle collectors, and others you might be able to sell to people that do crafts.

I used to sell some old bottles and probably will again some time in the future..  One of my old Treasure Coast bottles went to Australia.  Another was illustrated in a book on pharmacy bottles.  I like when finds like that are appreciated and used.

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I know that a lot of people read this blog.  I can tell that from the hit counter and google stats.  What I don't know is how often people actually try the techniques I explain.

If you adopted some technique that I explained or used some piece of information that I provided, I'd very much like to hear about that.

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There is Chinese company selling a knock-off of the Garrett Ace 250.  They copied the Ace, and their copy looks almost exactly the same.  It does have a different name, but there really isn't much difference.  I'd suggest not buying knock-offs like that.

It is bad enough they steal our industrial secrets and stealth technology, now it is metal detectors.

Even crafters are having trouble with Chinese knock-offs.  They browse sites like Etsy and eBay and then copy items.  They aren't the only ones the stoop to copying though.  Some U. S. sellers on those sites look for things they can copy rather than using their own creativity.

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Tomorrow look for pictures of new 1715 Fleet finds, including escudos.


There is no tropical weather to watch.  It looks like the surf will pick up next week, but only by about a foot.

Happy hunting,
TreasureGuide@comcast.net