test nuggets

[robbor]

I dont have any test nuggets, is it easy to melt fine gold down into a nugget say with a mapp gas torch?
Or can it be used as is in a small vial on string?

 

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[Reg]

Hi Jim,

What a beautiful specimen you have there.

You certainly know your Infinium and the nuances that are presented by the targets. That is the key with any detector to get the greatest success.

As for your question about masking on the TDI, yes, large iron objects do mask good targets as do thin tin can pieces. I suspect this will happen on any detector simply because of the fact all magnetic fields will take the path of least resistance which just happens to be through any ferrous material, thus there will be a concentration of a coil's signal in a piece of iron below it and less signal under other parts of the coil.

I don't see any way around this condition except to remove the ferrous objects. Now, when the ferrous object is a hotrock containing something like magnetite, a VLF can easily be fooled if the ground balance is off a little. If using the disc mode, any ferrous signal is so much stronger than a typical non ferrous signal that masking can occur very easily.

On a PI properly adjusted, the magnetite will not generate a signal but will still concentrate the field somewhat. In this case, it can or may enhance a good target signal close to the rock. At least it has in some of my testing.

So, just what happens or what can happen is really more complex than meets the eye. The variable alteration of the signal by ferrous objects is also dependent upon the distance from the coil. So, there is no easy way to predict just what might happen.

There is one other trick I learned many years ago when using a VLF and that is in really bad ground simply raising the coil a little actually can improve the depth of detection. This is especially true when using the disc mode. Actually, I learned this by watching a hunting partner and his techniques. He always did extremely well and at times would easily beat me in number of finds. It didn't make any sense because I thought I was following the best techniques by keeping the coil low and close to the ground to obtain the greatest depth. Well, I raised the coil a little and wow, what a difference.

Later I realized the field strength of ground signals dropped off much faster than target signals, so by raising the coil a little, neutralized much of the negative ground response but still left the target responses in tact. This made it easier to get a good response from the targets I was hunting.

The point of this is to let people know that sometimes what may not seem the best, may work the best. So, it doesn't hurt to try different things over areas that are productive. Who knows just what will happen.

Reg

 

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[Jim Hemmingway]

Thanks Reg, yes the sample in the photo above was a nice find, and coincidentally also takes a decent photo. Some samples do not photo realistically, while others look better than they should…at least with my older low megapixel camera. Obviously silver isn’t gold, but as specimens I’ve seen fairly steep price tags attached. I don’t sell, so can afford to hold with a philosophy that they’re just interesting rocks that make for enjoyable, memorable life experiences.

In fact, I’d intended to hunt gold this year, traveled the 600 or so miles only to find, despite assurances to the contrary, the private reserve campground closed for the season. There’s no arguing with road barriers down and 45 gal drums loaded with rocks across the road. I anticipated not having hydro access, and that was a decisive factor in buying the Infinium at the time. “AA” batteries are handy for extended excursions into the bush. My intended search strategy at the time, aside from sluicing (no dredges allowed…I’ve got a 2” Keene sniper), was to use Infinium to recheck any areas where VLFs indicated potential, since good size pieces have been found in the past. After a few days of cramped sleep in the truck and scouting the area, I returned to familiar territory. But the prospects looked good, and I’m going back.

The background info about iron and magnetite is an interesting read. Most of us realize that iron hits well, but may not have understood why. Your comment about keeping the coil a bit elevated over higher mineral ground reminds me of what I’ve read repeatedly in Charles Garrett rock hunting publications years ago.

In case readers may like to see a few photos of some minerals mentioned in this thread recently, the following photos are magnetite (black sands) in crystal form, a nickeline specimen, a small but handsome silver nugget, and an additional photo of a silver-calcite sample found this past autumn.



These are widespread in my search areas although the nickeline is rare elsewhere. Magnetite (a non-conductive iron oxide) is an abundant negative hot rock (yielding the well-known “boing” signal familiar to electronic prospectors) in my area. If the ground balance control is advanced further into the ferrite end of the ground balance scale beyond magnetite’s ground balance setting, magnetite becomes a powerful positive hotrock “zip zip” signal.



The nickeline is quite conductive, and that conductivity is directly related to size in reasonably pure specimens.



Size is not much of a conductivity factor with silver here beyond an ounce or so, whereas the purity and structure do play a major role. Shape plays a variable role, as most ores and nuggets generally exhibit a “roundish” shape.



This may be a very modest specimen, but it ranks as one of my favorites. It was the very first piece I found using a PI detector. It was exactly one foot deep, found just as darkness was settling down over a remote backwoods tailings area. I clearly recollect rubbing my gloved hand over the surface hoping to see an indication of silver in the waning light.

Reg, before abandoning this thread I want to thank you for posting the initial information regarding gold alloy conductivities. I would not have imagined that adding silver to gold would reduce overall conductivity. I recollect Steve mentioning this phenomenon elsewhere recently too. It’s a genuine pleasure to have this opportunity again to speak with you. Your instructive posts have helped me a good deal, and for that I also sincerely thank you. Please have a safe and enjoyable Christmas holiday everyone.

Jim.

 

[Reg]

Hi Jim,

I am glad to be of help. Now, to be honest, the info regarding the gold and how it changes or affects is relatively new. I always assumed gold was gold as did so many other people. It was the introduction and use of the TDI plus various posts pertaining to it that sort of pointed out the differences. One important post came from Steve Herschbach on the TDI forum where he mentioned the signals he was getting from gold nuggets. His signals were totally different from mine and that didn't make sense. So, I began a search over the internet trying to find out as much as I could about gold and gold alloys.

You would be surprised just how little is really written on the subject. It wasn't until I stumbled on to the site I linked to that things began to make sense. Most of my nuggets basically acted the same because most came from the same area. That made things worse because I really didn't have a lot of variation. I did have three larger nuggets that didn't fit the pattern but I attributed most of their differences to their characteristics.

One thing that fits now but didn't when I first read it several years ago was something Eric Foster mentioned. He stated that it was more difficult to detect gold when alloyed with silver. If I remember correctly, he stated that the difficulty increased with the increase of silver until they reached about a 50 50 mix and then things reversed. I really need to go search the PI forum for the specifics of his post on the issue.

Anyway, it was Steve's posts about the gold in Alaska and how it responded on the TDI that set the ball rolling. All I can say is the internet really does help expedite the learning curve.

Jim, happy holidays to you and your family and to all others reading this post. May your finds be many and glisten with silver and gold.

Reg