Written by the TreasureGuide for the exclusive use of the Treasure Beaches Report.
 |
| Five Sinkers Used in New Tests. |
Yesterday I continued my tests to see how well the Equinox conductivity readouts correlate with the electrical conductivity of the metals in common targets. Recently I did some tests on coins - both clad and silver. In the past I conducted several similar tests with various types of targets including gold, coins, tokens and a few others. Gold rings can produce a wide range of conductivity numbers. See The Treasure Beaches Report Direct From Florida's Treasure Coast.: 9/11/19 Report - Exploring the Equinox With Gold Test Targets. Reader Emails. Three Systems to Watch. , for example. You will find a variety of other posts reporting on conductivity tests in the TreasureBeachesReport.blogspot.com as well as in this blog. Despite all my previous investigations, I'd like to better understand exactly what the conductivity readouts mean and how to use them most effectively.
I'm not one to depend upon what someone says, what the theory is, or even what the manual says without doing my own tests to see how my metal detector actually works. Yesterday I did some additional tests to see how the Equinox readouts relate to targets made of various materials. For the most recent tests, I used a variety of lead sinkers. They varied from 3 oz. to .75 oz. There were three that weighed 1.5 oz. Of those three, one was egg shaped, one had a loop of another metal, and one was fish shaped. They were all dug a week or two ago. I'm assuming that there is no significant difference in the lead used for all five sinkers. You can see them in the photo above.
I'll give you my conclusions at the end. First here are the results of the tests.
The 3 oz. egg shape sinker gave a very consistent 21. That is what you might get from some other common targets. You can expect a similar reading from a zinc penny, for example.
The 1.5 oz. fish-shape sinker gave readings of 17 - 19. The 1.5 oz. sinker with a little hoop of another metal, gave a 19 - 20 reading. And the egg-shape 1.5 oz. sinker also produced readings of 19 -20.
The small 0.75 oz. sinker produced readings of 17 - 19 - the same as the 1.5 oz. fish-shape sinker.
As expected, my most recent tests with clad and silver coins showed a relationship between the conductivity of the metals in the coins and the Equinox readings. Since lead is much less conductive than either silver or copper, the Equinox readings for the lead sinkers should show lower readings.
Before I get to that, here are some of the results of my previous tests conducted with silver coins.
The Kennedy half dollar coin was 40% silver and 60% copper, while the other three half dollar coins I tested were 90% silver and 10% copper. The reading I got on them was something like 31 - 32 for the Kennedy and 33 - 34 for the other half dollar coins.
Comparing the 90% silver half dollar with the 90% quarters, the half dollars gave conductivity numbers that were about 4 points higher than the quarter on the Equinox even though the proportion of silver and copper were the same. That suggests that size matters as well as composition. Other things might also affect the results.
So, the coin tests showed slightly higher Equinox readings for the 90% silver than the 40% silver half dollars. But when the reading for the 90% silver quarter was compared to the reading for the 90% silver half, the half dollar coins gave a higher reading than the 90% silver quarter. It seems that the size of the object has some effect on the Equinox readings.Now for the new data. All the lead sinkers produced numbers within a relatively small range. The largest sinker gave a reading of 21, while the others produced readings of 17 - 20, again suggesting a possible size effect for objects made of the same metals.
Lead has a much lower conductivity than silver and copper, and the Equinox readings for the lead sinkers (17 -21) was much lower than the conductivity numbers produced by the silver/ coins (31 - 34). Although there does seem to be a good relationship between the Equinox conductivity numbers and the electrical conductivity of the metals involved, it appears that there are some other effects - for example size and shape effects.
Unfortunately, the conductivity numbers do not provide a definite target ID. Sinkers can produce numbers that are virtually indistinguishable from some pennies, for example. New pennies are 97.5% zinc and 2.5% copper. If you check the following chart, you'll see that zinc has a lower conductivity than silver, copper, and gold, but a considerable higher conductivity than lead, yet a lead sinker produces a conductivity number very much like a penny. The conductivity readings produce good information, but they do not tell you exactly what is under your coil. You'll have to use all sources of information at your disposal for the most effective dig/no dig decisions.
---
Conductivity and Resistivity of Metals
Material | Resistivity | Conductivity |
|---|---|---|
| Silver | 1.59x10-8 | 6.30x107 |
| Copper | 1.68x10-8 | 5.98x107 |
| Annealed Copper | 1.72x10-8 | 5.80x107 |
| Gold | 2.44x10-8 | 4.52x107 |
| Aluminum | 2.82x10-8 | 3.5x107 |
| Calcium | 3.36x10-8 | 2.82x107 |
| Beryllium | 4.00x10-8 | 2.500x107 |
| Rhodium | 4.49x10-8 | 2.23x107 |
| Magnesium | 4.66x10-8 | 2.15x107 |
| Molybdenum | 5.225x10-8 | 1.914x107 |
| Iridium | 5.289x10-8 | 1.891x107 |
| Tungsten | 5.49x10-8 | 1.82x107 |
| Zinc | 5.945x10-8 | 1.682x107 |
| Cobalt | 6.25x10-8 | 1.60x107 |
| Cadmium | 6.84x10-8 | 1.467 |
| Nickel (electrolytic) | 6.84x10-8 | 1.46x107 |
| Ruthenium | 7.595x10-8 | 1.31x107 |
| Lithium | 8.54x10-8 | 1.17x107 |
| Iron | 9.58x10-8 | 1.04x107 |
| Platinum | 1.06x10-7 | 9.44x106 |
| Palladium | 1.08x10-7 | 9.28x106 |
| Tin | 1.15x10-7 | 8.7x106 |
| Selenium | 1.197x10-7 | 8.35x106 |
| Tantalum | 1.24x10-7 | 8.06x106 |
| Niobium | 1.31x10-7 | 7.66x106 |
| Steel (Cast) | 1.61x10-7 | 6.21x106 |
| Chromium | 1.96x10-7 | 5.10x106 |
| Lead | 2.05x10-7 | 4.87x106 |
| Vanadium | 2.61x10-7 | 3.83x106 |
| Uranium | 2.87x10-7 | 3.48x106 |
| Antimony* | 3.92x10-7 | 2.55x106 |
| Zirconium | 4.105x10-7 | 2.44x106 |
| Titanium | 5.56x10-7 | 1.798x106 |
| Mercury | 9.58x10-7 | 1.044x106 |
| Germanium* | 4.6x10-1 | 2.17 |
| Silicon* | 6.40x102 | 1.56x10-3 |
Source: Electrical Conductivity of Metals (thoughtco.com)
---
We've had a couple days of good north winds and swells. I hope to get out soon to see what is going on.
 |
| Source: MagicSeaweed.com. |
Stand for peace.
Happy hunting,
TreasureGuide@comcast.net