Conductivity of Metals

[joecatch]

I am trying to understand why I haven't found any gold yet with my AT Pro. I also read recently here that setting the discrimination above 35 masks out some gold. So I went to the net and found the conductivities of different metals. The common ones are (in 10.E6 SIEMENS/M):

SILVER = 62.1
COPPER = 58.5
GOLD = 44.2
ALUMINIUM = 36.9
ZINC = 16.6
BRASS = 15.9
NICKEL = 14.3
IRON = 10.1

So then I matched up these numbers with the VDI readings of my AT Pro and they seem to line up pretty good with actual results. But they suggest that gold should come in right above pull tabs which are around 53-55. So in theory some gold should be between 53 (aluminium) and 80 (pennies).

Of course this does NOT take into account most of the stuff we find are alloys and not pure metal. And it doesn't say why discriminating out some iron masks out some gold. I have been passing up on targets in the 40's but will start to dig more hopefully to catch some gold instead of just foil! And I need to start digging more targets in the 60's too.

JC

[John in NC]

If you are digging pull tabs you'll get the gold.

[joecatch]

Pull tabs on my AT Pro run from 53-57. So the other day in the middle of a large school field I got a loud 53 so I thought either pull tab or a nickel. Instead I got this silver plated diamond ring. I am sure they are not real but I finally got a ring in the pull tab range.

JC

Originally Posted by John in NC

If you are digging pull tabs you'll get the gold.

[Lostlegion]

Size, shape and surface area change the conductivity of all metals. All rings are alloyed with some other metals so a 10k ring is a low conductor whilst the same size 22k may be a high conductor.

Most U.S. nuggets are low conductors whilst Alaskan/Australian are high.

Target I.D. isn't accurate with any detector. With gold rings you really need to dig everything above small iron.

[HarveyH48]

This isn't really my field of interest, when it comes to electronics, but have been reading and studying, with thought of building my own pinpointer someday. $130 for a Propointer, is kind of steep, for what's inside, and what it does, just my opinion.

A metal detector sends out an electromagnetic pulse, which conductive materials absorb, and then release back, which can be detected. Size, shape, and other materials between the object and detector coil, will effect how this all works, and I doubt there will ever be a detector that is 100% correct every target. There are really too many variables to give more than statistical guess on what's in the ground. Even the folks with thousand dollar machines, still dig trash. If you notch out signals, you are going to miss a few good ones. Trash is just part of the game, the more you dig, the greater the reward for doing a good think (collecting the trash, and filling in those holes).

[Left4Dead]

Originally Posted by joecatch

I am trying to understand why I haven't found any gold yet with my AT Pro. I also read recently here that setting the discrimination above 35 masks out some gold. So I went to the net and found the conductivities of different metals. The common ones are (in 10.E6 SIEMENS/M):

SILVER = 62.1
COPPER = 58.5
GOLD = 44.2
ALUMINIUM = 36.9
ZINC = 16.6
BRASS = 15.9
NICKEL = 14.3
IRON = 10.1

So then I matched up these numbers with the VDI readings of my AT Pro and they seem to line up pretty good with actual results. But they suggest that gold should come in right above pull tabs which are around 53-55. So in theory some gold should be between 53 (aluminium) and 80 (pennies).

Of course this does NOT take into account most of the stuff we find are alloys and not pure metal. And it doesn't say why discriminating out some iron masks out some gold. I have been passing up on targets in the 40's but will start to dig more hopefully to catch some gold instead of just foil! And I need to start digging more targets in the 60's too.

JC

I would guess if you get an iffy reading on you ID screen you may not dig it. This is my opinion why people would miss gold and other good targets. Put a chunk of tape over your screen and just give it a try. If it sounds good dig it. I know I used to you all vid detectors. Now I don't use a screen.

Also we all know that the way aluminum acts in the ground can be as conductive as silver. Or least make us think so. When it's smashed together.

[Bonesquat]

I dug this 14kt diamond ring...Comes in the very low foil range.



This next one came in a perfect nickel signal. 10kt



The third ring you see gave a classic pull tab signal. 10kt



Larger class rings can range anywhere from pull tab up to a copper penny signal. You really just have to dig EVERYTHING to get the gold. Some tiny jewelry won't sound of on my compadre unless it's set to iron!