Friday, June 26, 2020

6/26/20 Report - Incorrectly Marked Gold. If You Dont' Know Where You Want To Detect Do Some Sampling.


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

Gold Ring Find
Find and photo by Duane C.


Duane and I'd like to hear your opinions regarding the question he submitted below.


Unusual find beach detecting. A orange colored gold ring comes out ringing higher on my Nox than a typical 14k of its size. Higher numbers usually associated with higher carat like many 18k bands found prior. The color also closer to 18k than 14k. Originally believed it was 18k until I saw the marks inside. Surprised to see 14k not 18k. Tested at home with acid and electronic tester positive for 18K. The carat mark appears to be engraved not stamped. First one I’ve found like this. Makers mark maybe Cupillard but cannot find any further information on that maker. Ring appears no be marked wrong, odd one.

Mark on Same Ring Found by Duane.
Photo by Duane.


So what do you think about the item testing 18k with an electronic tester and acid test?

Send me your ideas.


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One of the most useful things you can do is sample various areas of the beach.  But sampling is a skill and must be done well to get the anything out of it.

You can't cover every inch of a beach.  There is just too much of it.  And you don't always know what some areas might be holding, so one good thing to do is take a sample.

Before I get into the details of how to do that, it will help to get some background information.  Unlike beaches, we know a lot about the distribution of IQs.   If you test a bunch of people, the average IQ should be around 100.  But if you test any single person, they will fall somewhere in a range between zero and something close to 200.  Fifty percent of the population has an IQ score between 90 and 110, and 95% fall between 70 and 130.  For IQ, we know what the distribution looks like.  It looks like the bell-shaped normal curve shown below.  The vertical access is the IQ score, increasing left to right.  So the most people have the average score of 100.




Source: Wikipedia.
If we were to flip a coin numerous times, we also know what that distribution would eventually look like (assuming a fair coin).  It would be binary distribution, like the one shown below.  If you only flip a the coin a few times you might get something like five heads and only one tail, but as you increase your sample size, eventually you'll get about the same number of heads as tails.



The point of that is, when you take a sample, when your sample is small, it may not reflect the overall population, so you have to take a larger sample to get a better sample of the total population, or in the case of metal detecting, the area.

When you are on the beach, you may not have a good idea of the distribution of good targets.  You might not know if there are any good targets at all within range of your metal detector, but as you do more sampling you'll get a better idea of what might be there.  You'll never know if your sample was sufficient.  One missed target can be a big deal.

I always remember several seasons ago when on Gold Rush TV show, Parker was thinking about mining a piece of ground and I wanted to shout at the TV, "Take some samples."   Eventually he got Tony Beets to do drill some samples, and I was so relieved.

On Bering Sea Gold you'll often see them panning a few samples.  Sampling makes a lot of sense when you do know how much, if anything, is there.  Rather than spending tons of time before you have any evidence of what might be there, why not do a little sampling.  If there is something there, sampling can also help you figure out how it might be distributed.

You can use your past experience and present goals to help you narrow down the area or areas you are interested in sampling.  You'll often be interested in some areas but not others.  Samples should be representative of the area  you are interested in.  You might want to sample multiple areas.  Some may look productive and others not.

With a metal detector it isn't like taking core samples.  You would scan an area with your metal detector using any of a variety of patterns.  One of the patterns I've discussed in the past is a zig-zag pattern, for example.  That pattern will allow you to scan sample high and low areas of a long narrow zone.

Samples must be representative.  That means the area sampled must be a fair unbiased sample of the area to which you want to generalize.  If you start by taking a small sample and get some evidence that the area might be worthwhile, you can then take a larger sample.  Sampling is a skill, which I can't discuss in great detail now.

To use an example we are now all unfortunately very aware of, we keep hearing about the number of COVID cases.  If you wanted to estimate the incidence of infections in the US you would make sure to have a fair random sample.  If, on the other hand, you are primarily testing those who seek testing because they have symptoms or have been in contact with someone who was infected or something like that,  that sample would be expected to have a higher incidence of infections than the general population - unless, unless of course there were also a lot of hypochondriacs in the sample. :)  Please don't make me spend about another 50 pages on that topic.  I'm actually trying to avoid it.

The quality of a sample is important, but so is the sample size.   A very small sample will have limited value.  There is usually a sample size that is large enough that if you repeat the sample you will get very similar results and below which, the results will vary wildly.

Think of the heads/tails coins experiment.  If you flip a coin three or four times, you might easily get all heads or all tails, but as you increase the number of observations your distribution will more closely resemble the distribution that you would expect, which is half heads and half tails.  You don't need thousands or even hundreds of flips to be pretty sure your sample distribution comes close to the expected 50/50 distribution.  But that much simpler example than most real-world problems.

A sample has to be representative, which means it has to reflect the characteristics of the area you want to know more about.  You can't just sample the wet sand or dry sand if you want to draw conclusions about the entire beach.  As you know, there are places that coins and other objects are much more likely to be found than others, whether you are talking about wet or dry sand.

I'll wind it up here for today.  Maybe return to the topic some other time now that a lot of the background has been laid.

Anyhow, if you don't know where you want to spend your time, you might consider sampling an area or multiple areas of the beach to see if there is any evidence that you should detect that area more thoroughly.

When you look at a beach and see several spots you might consider and don't have time to thoroughly detect them all, you might sample each one before deciding where to spend your time.

I know I didn't do a good job on this topic.  It would probably take a fifty pages to do that.  Anyhow, maybe I gave you something to think about.

I'll undoubtedly come back and try to clean this up.

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The surf is still small on the Treasure Coast and there is no tropical weather in the Atlantic on the National Hurricane Map.