Friday, July 25, 2014

7/25/14 How Not To Miss Gold: Detector Mode Test Results. Saga of the Central America.

Written by the TreasureGuide for the exclusive use of

Sample Gold Items For Detector Test
There is no detector that can identify any and every type of relic, watch, ring, or whatever with 100% accuracy. I am certain that you will miss some very good things if you simply pass over items because of how they display on an ID screen or because of the audio tone. You have to make a calculated decision concerning how much of what you are willing to miss. 

It is relatively easy for a detector to correctly identify modern US coins.  They can do that well, but the question is, is that what you really most want to find.

Not very long ago I talked about making those decisions in my post on Math for Metal Detecting.  I pointed out how a single good find can be worth more than hundreds or even thousands of coins.

Whatever your decision making process, there is little that is more important than actually knowing your detector, especially how it reacts to high value targets such as gold.   And there is no better way of getting to know your detector than working with known test targets.  It doesn't matter if you are hunting cobs or modern gold, you absolutely need to know how your detector responds to the items that you really want to find.

I did a field test of the ACE 250 not long ago.  It is a low-cost discriminating detector, that in my opinion is a very good detector for the price.  I used it for the following test.  I wanted to see how well it identified various samples of gold jewelry.   For me, these types of tests are mandatory for any detector that you want to use.

I got a sample of gold items that varied in size and weight for the test.  They are pictured above.  I labeled them 1 - 5 going from left to right in the picture.

The first thin ring weighs .04 troy oz.   The second weighs .09 troy oz.  The second is smaller but wider than the first.  The third weighs .23 troy oz., and the forth, .27.   The fifth is a bracelet weighting .67 oz.

The ACE 250 has five hunting modes;  coin, relic, custom, jewelry and all metals.  I tested the Coin and Jewelry modes first.

I put the targets on ground that I have used many times in the past (so I know it is clean) for such tests and ran my coil over the test targets.

In Coin mode the small rings labeled 1 and 2 were identified as nickels.  Fine!  You might think you are digging a nickel and be surprised to find a small gold ring.  No big problem.

Still in Coin mode, items 3 and 4, were not detected at all.  By that I mean there was no audio tone.  

I ask you, would you rather detect a clad coin or the average size gold ring?   If you don't want to dig anything but coins, that is fine, but realize what you might be giving up.

Still in Coin mode, the bracelet (item 5) was identified as a nickel.   Hope you are digging nickels if you go over a bracelet like that.

In Coin mode, you will dig smaller gold items that display as nickels.  You will, however, miss larger gold that falls in the pulltab range.

In Jewelry mode item 1 jumped back and forth between nickel and foil on the ID display screen.  Item 2 was identified as a nickel again.   Items 3 and 4 were identified as pull tabs.  And item 5 was identified as a nickel again.

If you want to find gold in Jewelry mode, you should be digging nickels, foil and pull tabs. 

This test was done using one particular detector.  Results with other detectors can vary, but these test results should show you how important it is to know your detector.

To summarize, if you were using either the Coin mode or Jewelry mode, you very well might have missed items 3 and 4.   That is two out of five gold items.   And they are pretty typical rings, which makes it even more important.

In Coin mode, you would not have detected them, and in Jewelry mode you would have misidentified them.

A lot of guys use Jewelry mode rather than Coin mode when hunting and say they find more coins in the Jewelry mode.  The Jewelry mode does not discriminate (eliminate the audio tone) for as many non-coin items. 

In this test it should be noted that I'm using a best-case scenario.  Items were on the surface and not near other items or junk which could have added additional mistakes.  Also deep items in the field may not be identified exactly the same as shallow items.

As I explained when I talked about Step Searches, I would not exclusively use a single mode on a promising area, but would switch modes and also detectors and cover the same ground multiple times.   What one detector or search mode misses another might not miss.  That is one big reason for going back over the area after having analyzed the area and likely targets.

This inexpensive detector has already found good numbers of coins missed in areas heavily hunted by much more expensive and powerful detectors.  Each different type of detector has its own specific strengths and weaknesses.  That is another good reason for searching the same area multiple times with different detectors.

Some detectors are very sensitive to electric lines and underground cables, for example.  Some are good at target separation.  There are different things that will allow one detector to find what another, even another more powerful detector, will not find.

I found this test enlightening and hope you did too.

I'll cover the Relic and All Metals modes tomorrow.

The site of the Central America had not been worked since 1991 until a court-appointed receiver awarded a contract to Odyssey Marine Exploration to salvage what remains on the Central America with the hope of obtaining more treasure and paying back investors.  Odyssey Marine has since recovered 43 solid gold bars, 1,300 $20 double eagle gold coins, and thousands more gold and silver coins.

Here is the link to that interesting story.

On the Treasure Coast we're still stuck with a South wind and East swell and only a one foot surf.  That has been the pattern for a long time now.  Still watching for a change.

I think this was a very useful post.  I hope you think so too.   It explains in an empirical way much of what I talk about.  More tomorrow.

Happy hunting,