Conductivity results, thanks Eric but...

[Anonymous]

Thanks for your conductivity test results Eric, but you know how it is with answers - they always result in more questions ). What is needed now is a series of tests that relate conductivity directly to detection range. For example, can a metal with a 90 conductivity score be detected twice as deep as one with a 45 score?. And if a gold nugget only scores 9 yet we can detect it at say 4", can we therefore detect the same sized pure copper at 10 times that depth? ( no way, but you see the point!). Cheers from OZ, Chris Hake.

 

[Anonymous]

Hi Chris,
You are right, such information only leads to more questions. The main point really is that metals are rarely pure and their detectability depends to a considerable degree on their constituents. The common assumption is that metals like gold, silver, copper etc are good conductors and should be easy to detect. In reality their conductivity, and hence range, can be severely modified by other constituents. It all started with earlier posts I made about the detection range measurements I did on gold/copper and gold/silver standards back in the

 

[Anonymous]

Hi Eric and Chris
I will add a bit more confusion to the subject,I have flat 20 gram nugget from W.A that can not be picked up more than 13 inches,and yet try a 5 cent Aussie cupro coin which is half its size and thickness and it comes in at better signal.A friend told us of a 5 oz nugget that they detectored in W.A at 10 inches in cap rock at a dry blowing patch,which was a very faint signal,it was a very flogged area which should have been picked up,so you could say that there is no simple answer to the mystery.
Regards Frank Wallis

 

[Anonymous]

Hi Frank,
Some nuggets I've seen are not solid chunks of gold, but look a bit like the metallic version of osteoporosis. Any cavities or discontinuities within the nugget will break up or attenuate the eddy current path, with the result that the net conductivity is even less than that caused by alloying alone.
Eric.

 

[Anonymous]

Hi Eric
The nugget that I have is very solid ,and I have a bit fun from time to time asking friends to detect it,they are surprised at the low response to such a solid nugget.
Regards Frank Wallis

 

[Anonymous]

Frank, it would be nice if someone decided to get an assay done on these undetectable nuggets. Sure, it would cost about $100 and a little hole would be drilled in the nugget but heck, all is fair in the interests of "science"! The average for Kalgoorlie area nuggets is 91.6%Au & 7%Ag. Steve D said the Sth Oz undetectable nuggets were around 94%Au, which is baffling!. I would have guessed they were about 50/50 Au/Ag or one of the tellurides, possibly Rickardite which is a copper telluride Cu/Au. Cheers, Chris Hake.

 

[Anonymous]

Hi Chris
I been told that there is a spot between Leanora and Laverton were the nuggets are very hard to detect,you could say a bit tricky.
Regards Frank Wallis

 

[Anonymous]

HI all
Here in cold downtown Gippsland we have one spot that produces nuggets that are almost impossible to detect with SD's but the main problem is that they are thin flakes approaching foil in thickness and have not got enough mass to carry the eddy currents required by PI detectors. They are, however, no problem for VLF detectors because they work more on the skin effect so that surface area is more important than actual mass.
Unfortunately Eric I dont have a bit big enough to test on your conductivity meter.
Piotr I you are listening could you also do some tests with your conductivity meter on the same type of coins as Eric tested? Would be a very interesting comparison.
Cheers
Steve D

 

[Anonymous]

Now thats got me thinking, Frank. I think I might know the area, and I wish I still had an XT17000 to go check it out. But I'll borrow an XT and check it out for sure and if anything yellow crops up, I'll get an assay done on it. Cheers, Hakey.