Tuesday, July 29, 2014

7/29/14 Report - How Small Silver 1715 Fleet Cobs Identified by Metal Detector Target ID. Cape Verde Storm Season Begins.

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

Snall Mexican Cob Remnant Used In Test
Before I begin today, I need to make something clear.  The tests that I have been doing are not just about a single detector.  These tests, although they use a particular detector, illustrate many of the points that I've made many times in the past, such as the dangers and imperfections of target ID and discrimination.  They are real, and they can be very important.

Another point that I am making with these tests is that you have to know your detector to get the most out of it.  If you don't you could be missing a lot of good targets - perhaps the best targets.

One day, using five different sample gold jewelry items of different sizes, I showed that if you did not dig items identified as  pull tabs, you could be missing something like 40% of the gold items that you put your coil over.

Another Small Half Reale Used In The Test
One more important thing I am illustrating through these tests is a systematic method anyone can use to learn how their detector responds and what it is telling you.  That is perhaps the most important thing to learn from these tests.  These types of tests can be used with any detector and any type of target.

I looked at how gold was identified by one detector a couple of days ago, and a few pieces of silver yesterday.  Overall, I've found coin ID on the Ace 250 to be generally excellent, but gold not as good.  That is to be expected.  Gold items are unique in size and shape and even composition.  Gold items vary in purity and the alloys used.

Today I'm going to look at how the same detector identified three small beach-found silver cobs.  Two of the test cobs for today's test are shown above.

As with the other tests, I tested using four of the detector's modes: All metals, Coin, Jewelry and Relic modes.

For the small cobs I used a badly worn half reales, which, as is true of most cobs found on the beach, were significantly underweight. 

The first weighed 0.015 troy oz,, the next, .07 troy oz., and the third, 0.2 troy oz.

The top picture above shows a small cob remnant, which is so small and worn that it would be underweight for even a quarter-reale, even though it is a half reale.

It measures about 5/8 inch across at its widest and barely over one half inch long.

These test results are easy to summarize.  The ID in all four modes was the same for all three cobs.  In all four modes all three cobs were identified  as a nickel.

That isn't bad.  Yes, you can't tell the difference between a cob and a nickel with the target ID, but at least the cobs didn't ID as a pull tab or something else that you most likely would not dig.

I was surprised that the detector identified the very small reale (0.015 t. oz.) as a nickel.   This inexpensive detector very clearly detected a very small piece of silver.  Not bad!  And it did not ID it as junk.

That is good news if you want to use a detector like this for finding cobs.  I haven't used this detector in the field for that purpose yet, and the one serious deficiency of this test is that it was conducted on dry sand, not mineralized or wet sand.  That will be a test for another day, although I most likely would stick with my much more costly detectors if I were really hunting reales on a beach.  Another test for another day would be to see how much depth effects the results.  These tests were done on surface items.

As it is, I am pleased with the effectiveness of this detector.   My first field tests in an old yard and woods, went well, as did the tests that I conducted since then.

Questions remain to be investigated, but I am getting to know this detector and its strengths and shortcomings.  I learned that if I'm searching for gold, I need to dig items identified as nickels or pull tabs.  If I want to detect small cobs, I need to dig items identified as nickels. 

I haven't test larger reales yet.   The smalls identified as nickels, while the large (0.6 t. oz.) silver bullion coin that I tested yesterday, was identified as a half dollar.  This test did not test reales in between 0.2 t. oz. and 0.6 t. oz.   I'll have to do that some time.  I wouldn't be surprised if there are some in that range that will ID as a pull-tab.  We'll see.  For now, I know that the target ID would not cause me to miss small reales if I dig targets identified as nickels, or larger silver coins.

It is the time of year when the Cape Verde storms start coming across the Atlantic with greater frequency.  August through October are the peak months to watch for those storms.

Here is a link to a good article about the Cape Verde hurricanes


Right now there is a tropical disturbance about a 1000 miles southwest of the Cape Verde Islands that has a 70% chance of becoming a cyclone in the next 48 hours.

According to the predictions, the Treasure Coast will be stuck with a one-foot surf through next Monday.

Happy hunting,