More finds at US Army Hospital site 2ndWW

[Gila Marc]

My take on this (please correct me if I'm all wet!): I believe it has to do with phase shifting and eddy currents. In air a search coil has a symetrical somewhat cone-shaped field of electromagnetic flux. Any interference within this field causes the fluxlines to shift in an attempt to bypass the intruder (kinda like water in a stream going around a rock). Any mineralization in the soil causes minor phase-shifts all the time, thus the need to ground balance. Greater phase shifts cause a "wow" in threshold, and a major interference will cause eddy currents to form on the intruder and a signal in the headphones.

Phase shift MAY depend on conductivity, but eddy currents do not. They depend on the size of the "silouette", or surface area facing the coil. That is why a deep aluminum can will sometimes sound like a silver quarter, though their conductivities are very different the eddy currents may read similar. I'm sure everyone has noticed that a silver dime will read lower than a silver quarter, though they have the same composition. I'm convinced this is true of gold also...same material, different surface area. The machine is trying to reconcile the phase shift and eddy current readings to come up with a plausible answer, which may sometimes be confusing to us.

But then I could be entirely wrong.

Marc

 

[Golden]

I reckon you're dead right Gila Marc. Our one dollar and two dollar coins here in Auatralia, are both the same in composition, both different in size, yet both give different numeric readings on the Quattro. Same goes for pre-decimal coins. For example: the half penny and penny have the same composition of metals, but due to the differences in size of the two, they read numerically different. I found this also with some silver coins. Which now brings me to the thought of gold nuggets. We've tested our different sized nuggets, which come from the same locality, only differing in sizes, and know to be of the same percentage of gold, but read differently on the Quattro screen. This also occured with the Explorer 2, with it's two dimensional ferrous & conductivity readings. The best way for any one to see for themselves is to grab two coins of the same metal composition, but different in sizes, and to do your own test. Hence is the reason why being too specific with your discrimination in a gold field, while looking for gold nuggets, will leave some there for others to pick up.
Angela

 

[Golden]

are you a metalurgist or geologist? Because I love to talk to people like yourself because I'm fascinated like yourself about gold, and dying to learn more and more about it! There seems to be a lot of mystery surrounding the subject of gold.
We also get here in Australia what appears to be gold crystals, and other forms of crystals like wire gold, as you explained. Which by the way are very highly sought after for their specimen value. Some gold crystals, as you touched on, may be not crystals at all, but gold that has gone into a solution state, and now deposited itself in the oxidized zone, and taken the place of iron pyrite or other forms of pyrite, and taken it's shape. Hence the cubic shaped crystal we now have of gold. As you know, gold doesn't have to be in a molten state to be transferred from one location to another. (Which can occur at room temperature conditions). With a lot of the placer gold (we call it alluvial gold here), we still don't know how some of the nuggets are formed. For example, how would a river cause a nugget of over 2000 ounces to travel at distance from its source? Which could be explained by the bacterial processes. We do know that this bacterial process is not just a theory, because we are now growing gold in lab conditions at the McQuarry University in Sydney. Just think of it, instead of growing potatoes, we can grow gold! WOW! What I believe they've found (and I'm not an authority on this), that the bacteria forms small platelets of gold like armour over its body, and when it now transfers itself (not sure how this works) to another piece of gold (seed), it dies, leaving a small residue of gold over the seed, and this process continues to happen for many years, resulting in it's growth, similar to coral. Hence the appearance of growth rings. The amazing thing about this bacteria, is, it is able to live in some extremely harsh conditions, and has been found in drill core samples taken from holes over 4000 metres deep. I'm not sure if this is true, but I've heard that some has been found in metiorites believed to come from Mars.
So, the moral to the story, don't leave those worked out patches where you've found gold nuggets, because in 15 years time, they may be of a size that you detector can now pick up. They may have been replenished!
Angela

 

[Gila Marc]

I've never tried a Minelab for gold, but I've heard the Minelab VLF's aren't too good at locating really small gold pieces. The GP series of Pulse Induction machines are very good, but are designed for larger nuggets at great depth. Here in southern Arizona nearly all our native gold is extremely small, so most people use a dedicated gold VLF like the Lobo or Gold Bug. They can find the most minute pieces of gold at reasonable depth, but won't penetrate nearly as deep as the GP's. Then again, the GP's won't find such small flakes at ANY depth, so it depends on the size of gold you expect to find.

Marc

 

[Hard Nosed Dave]

http://en.wikipedia.org/wiki/Gold

 

[Gila Marc]

Angela....no, I am neither a geologist nor a metalurgist. I have learned most of what I know first-hand through a lifetime of working closely with gold as an assayer and refiner. It fascinates me probably as much as it does yourself. I MUST do a little research on this bacteria thing! The more you say about it, the more interesting it gets! So we have little "gold plated" bugs running around!

I know from experience that gold doesn't have to be molten to move or change form. I've worked a lot with ionic-gold solutions at room temperatures and below-boiling temperatures, mostly in electrolytic processes for deposition on cathodes. I've also deposited gold onto "seed" metals without electricity in high pH environments, and have dropped elemental gold from acidic ionic solutions by introducing weak ferrous sulfate (iron and sulphur....pyrites?). Sometimes I feel a kinship with the ancient alchemists!

My point is this: If all we are saying is true, then through some as-yet unknown process the little bacteria obtain a gold shell. Perhaps, considering the extremely harsh pH environments the little guys thrive in, they are not actually "growing" gold, certainly not creating it, but merely providing another, maybe faster, means for gold to be brought from ionic to elemental state and deposited on the "seed" particle, somewhat like nacre on a pearl. This could provide for the growth of nuggets in areas not in direct contact with the actual gold-bearing ionic solutions, and also account for the "growth rings".

Hmmmm...interesting. We need a metallurgical chemist to weigh in on this.

Marc

 

[beachguy777]

Boy, that's a great answer Gila. Believe it or not it makes sense to me. I'm not that astute on all this, but I'm currently reading a book by Charles Garrett, and he goes into the eddy current thing and the fact that a bigger surface area will read stronger. That would seem to explain why the different size pieces read different. Thanks very much for the response. That's very interesting and informative.

 

[Gila Marc]

On re-reading your message I noticed your comment about being too specific in discrimination and thus missing gold. In our area, using a dedicated gold machine, we normally use NO discrimination at all. With no discrimination circuit running, we get very good depth and the sensitivity to locate the small flakes that are our mainstay in the local gold fields. That's why the LoboST and Gold Bug II are so popular here.

Our gold-bearing areas are not too trashy so we can afford to dig all signals. Of course we find a few old bullets and shell casings, sometimes the remains of prior prospectors leavings, but even these are sometimes worth digging for us relic hunters! Try your machine in an all metal mode and see what happens. In the end, you may have to go to a true dedicated gold machine to get the small stuff.

Marc

 

[Golden]

thanks for that! We actually do what you do also. We don't use any discrimination on the gold fields, even though there is a lot of iron trash. The reason is because sometimes you will get a nulling over good targets, if you had some discrimination. As for the Quattro, it's more specific to being a relic/coin hunting machine, and though it picks up gold rings, and other gold jewelry, as for nuggets I think you'd be best using a specific gold detector for that. If you really are serious about getting gold. But the Quattro could very well read nuggets in the ground, if they were surface deep. A lot of the nuggets we have dug were as deep as six feet down, prior to digging they give a faint, weak signal, but as you dig closer to them, the signal becomes stronger. I got a Minelad SD 2000 (which doesn't have discrimination capabilities like the later models), and usually use it to go for gold.
Golden

 

[Gila Marc]

Wow!!!!! Six feet??!!?!!

How big was that nugget anyway???

Marc

 

[Golden]

don't know what I was thinking. I meant to say we've dug nuggets down to 60 inches (around two feet), but w have pulled out iron about 3 and a half feet down. So, sorry, it would have to be a pretty damn good detector to go down 6 feet! Sorry to raise your eyebrows there! But I wish!....

 

[Gila Marc]

No problem!!

We still use the archaic "feet and inches" measurement system here, but I assumed you meant 60 centemeters, or 2 feet. But then again, you COULD have one super detector....or nuggets the size of a light cruiser!

Joking, of course!

Marc

 

[beachguy777]

Golden, did I read you right, saying you got signals six FEET, down. How big were those nuggets? Wait a minute while I pick myself up off the floor on that one. Please explain that one for me.:|

 

[beachguy777]

60 inches is:| 5 feet, at least here in America. Not trying to give you a hard time, but even if you dig them 2 or 3 feet, HOLY MACKERAL there SAPHIRE, that's pretty darn deep. I still would like to know how big those nuggets were, and how big was the search coil you were using. That's really deep.!!!!!!.:|

 

[beachguy777]

Golden, I know I'm giving you a lot of flack on this, but I got to thinking that I think I remember an old post by someone who said they found coins a deep as 2 feet. I'm sure if it was a relic or something bigger in size it would go even deeper, so maybe I'm out of line to question you on that. I'm honestly interested though, cause especially if it's a small target, that's really amazing. Hope you respond with out "kicking my butt" on this one.:|:O:|

 

[Golden]

but I had everyone going on that, didn't I! Hi Marc, I've gone down two feet with the Quattro in the sand for large sinkers. The Quattro will read them at that depth. To be sure, we took a measuring tape with us, and measured the hole. That's how we got the depth corect. We even did a depth test between the Explorer 2, the Quattro and our friends Soveriegn. The Sovereign didn't go as deep as the Quattro or explorer (which by the way were on a par), but I think with a different coil on the Sovereign, you would get a better depth.
Golden

 

[Gila Marc]

Those are great finds, for sure!!

Those old coke bottles are neat. I have found several, mostly broken, around here also. Those were the days of refillable bottles, so the bottom designation must have been where the bottle was made, not where it was filled necessarily. I'm sure they got around some.

I've found bottles here marked San Bernadino, San Diego, Phoenix, etc. I found a really nice 6 Oz. unbroken one marked "Yuma Ariz.". It must be kinda rare. I saw on the Sanborn Maps for 1927, I believe, that there was a bottle plant here in the past. They couldn't have made THAT many.

Anyway, congrats! Great finds!

Marc

 

[beachguy777]

Hey Gila, where the heck do you live, generally, at least. When I saw Yuma, San Diego, etc., my ears preked up. I live in San Diego, but I lived in Yuma for a little while one summer, and I've been all over Arizona. I'd love to detect in Yuma sometime, if I can get away with it, or Tuscon, or any of the older towns in AZ., but I know I need to be careful and do my homework, because I believe Arizona must have a lot of historical and guarded areas because of the old cowboy days. Anyway, I've also been through Gila Bend. Is that where you got your name?:|

 

[beachguy777]

Alright there Tiger. You got me on that one! I knew you were just testing us on that, Ha Ha, but, your still fun, I don't care what they say about you. Of course, I'm kidding about that last part, I've never heard anything bad said about you.:|Well.... let's see here. Getting a little more grounded on this conversation, (no pun involved), I'd say that 2 feet deep qualifies the Quatro, otherwise known as the "big blue meanie", to me at least, is one heck of a machine. Do I hear an Amen, to that?:|

 

[beachguy777]

I used to buy those bottles, (with coke in them) when I was a kid down at the store for about 7cents a bottle for the small ones and 12 cents for the 12 oz. size and about 25 cents for the "great big size, which I don't remember how many ounces it was". They were all refundable at the store to turn back the bottles for money. Boy, am I ever getting nostalgic on that one. That was a happy time in my life, and down the street from that store was an old trolly car barns place where they kept the trollys at night. It's gone now, but I'd sure like to detect around that area.