Hot Rocks and Tin Foil

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Whilst gold prospecting in the Golden Triangle I have encountered a lot of degraded tin foil at the head of gold bearing gullies where nuggets were found-usually next to surfaced areas where the diggers set up camp.Tin foil was in use from the end of the 19th. century till mostly 1910 when aluminium foil was produced,but it continued until around WW2.
Some areas like around North Dunolly have a very heavy concentration of small hot rocks.
Found only a few bent nails but the tin foil is of great concern as I have wasted a lot of time and energy digging it up.
I have a 10 month old VLF machine which can easily be set up to identify hot rocks or mask iron nails,but I have yet to learn how to set the second tone break to mask tin.I need an exact setting so as not to mask out gold. I go by tones alone.Have a 2,3 and 4 tone discriminating modes on my detector so there should be some way to mask the tin.I have not seen tin mentioned in my manual or how to mask it with the various tones.

If anyone has solved this problem I would be obliged to hear about it as the prospecting season is not far away.
 
The problem stems from those bits of tin or alloy not being equal size so when you get your setting right you then find another bit and it is either flat or screwed up so depending on which it gives a different ID and then it breaks the tone and it's back to square one, It is a lot like ring pulls, On average there are 4 basic types and each one has it's own ID and then you find a fragment of one and that adds to the problem,

Due to the shape and size of what you are finding are so variable you are never going to be able to set the controls in the right place So I would not worry about that so much but saying that there is a light at the end of the tunnel, Because you are finding so much of this stuff that means either no one has detected there OR they found the same problem as you and gave up and walked away, The up side to this means that there are still some good targets in the area, So you can either set your disc/tone break in the normal position and carry on as normal or walk away or you can Grid the area in 20m squares and give it a proper going over, Your machine can handle the junk so I would set the disc/TB fairly low and stick at it.

In an area like that My settings would be Ground balance and then throw a rusty 2" nail on the ground and turn up the disc so it only just knocks out the nail, Any higher and you will knock out rust stained Gold and Tiny Nuggets, This is another reason why Prospectors dig it all, That place sounds like one of the worst areas a person could come across so you have 2 choices either do the above or walk away, Personally I would hit it hard for weeks on end 12hrs a day til it was done. Oh and try using a smaller coil not so much for the junk because the detector will see less of the ground and allow you to run the Gain up higher. you can always go over it with a bigger coil later or vice versa.

Hope that helps.
 
oldtimerROB said:
I have a 10 month old VLF machine which can easily be set up to identify hot rocks or mask iron nails,but I have yet to learn how to set the second tone break to mask tin.I need an exact setting so as not to mask out gold. I go by tones alone.Have a 2,3 and 4 tone discriminating modes on my detector so there should be some way to mask the tin.

Discrimination is not a perfect science. It's an aid but different shapes, alloys, depths and surrounding ground mineralisation can all affect the ID.

Which machine are you having issues with?
 
ProspectorPete said:
Maldon Gold Centre said:
Which machine are you having issues with?

The only one worth having in heavy mineralised areas of the GT apparently :lol:

PS: Sorry, had to be done by someone and since I've had a crap day at work I'll happily cop the kick in the arse from Mods ;)

Not to mention that your machine is the only true way to deal with hot rocks, :Y:
 
ProspectorPete said:
Couldn't resist although I thought it was great he actually asked a proper question of once :Y:

And RR gave OTR the best honest answer anyone asking the same question could expect :Y:. I've never owned or used a VLF, I like the question and considered the thread closed after post 3. Couldn't agree more with your coment though, no offence OTR but you do take it to the limit imo.
 
Ship of fools said:
Back on topic!
I have a smaller coil, this appears to reduce sensitivity as well as depth, is this normal?
Matt T

A smaller coil should not reduce sensitivity if anything it should be hotter, But due to the small size it sees less of the ground which in turn allows you to turn the Gain up higher boosting the sensitivity to smaller Items, depending on the model of your machine and the type of small coil it is can and will have varied effects,

The frequency has a slight effect on the sensitivity on some VLF detectors where as some brands/models rely on the internal Gain multipliers which can have a huge effect as to how well they can see very small targets, remembering that VLF machines use frequencies up to 30khz, where as higher frequency machine can get away with using less gain in order to see targets of the same size, The drawback of higher frequency machines is they can become more noisy when the user tries to run them too hot where the lower/mid frequency VLF machines are a bit more flexible, So running a high frequency machine at a reduced Gain can and will show better results on fine Gold but this is where the skill of the user comes in to play, recognizing the signs will make all the difference,

If your small coil is a DD then it will have almost the same sensitivity as most other DD's made for your machine, But if the coil is a Concentric the it will be a lot hotter than a DD of equal size.

hope that helps.

J.
 
Tin foil. Its a curse I dug a whole 60cm into calcrete only to find it was tin foil. Talk about being pissed off. I even detected the hole after it was out just in case but no such luck.
 
Thanks guys.
I was thinking the same, smaller coil less depth same or better sensitivity.
Internal gain multipliers Well above my abilities!
Im away from home at the moment, when I get home Ill do some direct comparison air tests and post in AT max section.
Coils are standard 11x8 and smaller 8x5 both Garrett coils, I wanted a Nell snake but was told they only have one for the pro or gold.
Just wondering why the Nell wont work on the other ATs but the Garrett coil will?
Matt T
 
Ship of fools said:
Thanks guys.
I was thinking the same, smaller coil less depth same or better sensitivity.
Internal gain multipliers Well above my abilities!
Im away from home at the moment, when I get home Ill do some direct comparison air tests and post in AT max section.
Coils are standard 11x8 and smaller 8x5 both Garrett coils, I wanted a Nell snake but was told they only have one for the pro or gold.
Just wondering why the Nell wont work on the other ATs but the Garrett coil will?
Matt T

Smaller Coils will have less depth in Air Tests, But sometimes in the ground due to mineralization they can have better depth, because using a larger coil will multiply the amount of mineralization the detector see's because it has a bigger surface area so it takes a bigger picture of the ground, A large coil can blind the detector in hot ground where as a smaller coil can let you work the same ground albeit at a reduced pace.

Your AT does have gain multipliers and they are quite powerful,

J.
 
MGC. I was using the Impact in GEN mode with discrimination set at 01,the least setting so as to identify small hot rocks. Then I went on to DI3 on the last day I was there and it went deeper than GEN. I was on this exact spot up at Wedderburn in 1982 and found a melon seed nugget with a Whites Coinmaster 5000D. It is undisturbed virgin ground next to extensive surfacing of the entire gully. It has small gums for shade and the old timers obviously camped there judging by the tin foil. But many gullies were found much later there after the gold rush in 1860. There were prospectors in the area in the 1890,s depression and obviously hit it rich with this particular gully as they could afford chocolate. Back in 1982 my Whites found the small nugget but I did not pick up any tiny bits of tin foil with the 8 inch coil. I could go over this site again in the DI3 mode and mask out silver with the tone break as I think tin is closer to silver than gold but have to consult the manual on how the set the second tone break.The first one is at 15 and in the DI3 mode I think gold comes up around 35/40 on the ID. I can save a piece of tin foil and set the tone break to mask it out.I am new to DI3 and have been using DEEP mode and set the tone break to 15 to mask out rusty nails,as the factory setting of 40 gives a high tone for nails.
 
oldtimerROB said:
MGC. I was using the Impact in GEN mode with discrimination set at 01,the least setting so as to identify small hot rocks. Then I went on to DI3 on the last day I was there and it went deeper than GEN. I was on this exact spot up at Wedderburn in 1982 and found a melon seed nugget with a Whites Coinmaster 5000D. It is undisturbed virgin ground next to extensive surfacing of the entire gully. It has small gums for shade and the old timers obviously camped there judging by the tin foil. But many gullies were found much later there after the gold rush in 1860. There were prospectors in the area in the 1890,s depression and obviously hit it rich with this particular gully as they could afford chocolate. Back in 1982 my Whites found the small nugget but I did not pick up any tiny bits of tin foil with the 8 inch coil. I could go over this site again in the DI3 mode and mask out silver with the tone break as I think tin is closer to silver than gold but have to consult the manual on how the set the second tone break.The first one is at 15 and in the DI3 mode I think gold comes up around 35/40 on the ID. I can save a piece of tin foil and set the tone break to mask it out.I am new to DI3 and have been using DEEP mode and set the tone break to 15 to mask out rusty nails,as the factory setting of 40 gives a high tone for nails.

Did you bring any bits of the tin home so you could play with the settings, I might pay to keep some of the other bits too but you will still need to buy a small test nugget once you find a setting that can deal with the hot rocks and the tin foil. It won't be easy but it can be done.
 

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