Jul 16, 2012, 11:44 PM
Gold Coin Cache Hunting--Technical Question
I've got a site where they may be a cache of gold coins. It would be 2-4 feet deep in a clay jug. It's buried in red clay, which is very mineralized soil. I'm trying to figure out which type of equipment to use, such as a large PI loop, GPR, magnetometer or maybe a Electromagnetic (EM) antenna, like OKM makes. I've been told that a cache of gold coins will not show any bigger (surface-area-wise) than a single coin, even though they are touching each other, but a solid a gold bar would show a bigger surface area, because it's solid. I was wondering if this is true, and if anyone could recommend what equipment would work best in these conditions. Per the Lorenz site, (a German company that makes very good PI units) their 1 meter loop is too big to pick up on a single coins and their double-d coil (the one the can differentiate between ferrous and non-ferrous) doesn't go much past 15 inches on a coin. I was also told by a GPR manufacturer that GPR does not work well in mineralized soil. Not sure what to do.
Last edited by mbryant01; Jul 16, 2012 at 11:46 PM.
Jul 17, 2012, 08:35 AM
The FIRST thing to do is slow down before you throw your money away on a machine that is not going to work for you. If you are serious, about recovering this "possible" cache, and it is in fact within 40" from the surface, a Minelab GPX 5000 with a 20" coil will find it easily. I said EASILY. I'm a gold prospector and I have personally and personally witnessed single gold nugget recoveries at 30"+ on 2-4oz nuggets.
Originally Posted by mbryant01
Don't fall for cock-n-bull advertising copy, pretty little underground multi-colored graphics and technology mumbo-jumbo. You did exactly the right thing by doing your due diligence and checking it out yourself before purchasing. Good Luck!
Jul 17, 2012, 04:57 PM
Get a two-box unit, if the stat's you're talking about are really true. Something lunch-box sized like that, is perfect for a two-box (and you'll simply not hear the pesky individual coins, nails, tabs, etc....).
But let me tell you, cache stories are a dime-a-dozen. I wish I had a dime for every "sure fired" treasure lead I've heard from convinced friends, relatives, and passerbys, in my 35+ yrs. of this
Metal detecting is my one worldy vice!
Jul 17, 2012, 05:16 PM
While it is true that each coin will give an individual response, a mass of coins will give a larger response than a single coin. The percentage increase is difficult to determine but I would say 25-40%. Partially because of the area of the mass and partially because of the combined response of each coin. I have buried caches and can detect them from a much greater distance than a single coin. Look at it this way, ring a single small bell and you may only hear it from 50ft away but ring a dozen small bells and you will likely perceive the combined ringing from a much greater distance. Good luck with your search.
When it comes to detecting, you will always find me "out standing in the field".
Jul 17, 2012, 06:26 PM
The question is will an 18 inch coil on a pulse induction machine find it? The answer is yes if the ground is not extreme. In the 20 inch deep range, no problem. In the 40 inch deep range, you might need a one-meter square coil. In moderately hot ground the 18 coil will work even at 40 inches on a handful of coins.
Jul 17, 2012, 07:56 PM
That's interesting. A guy at KellyCo told me, unless I misunderstood him, that a gold coin cache will not register, surface area wise, more than a single coin even if the coins are touching each other. So your saying that it will register like a larger object would.
Jul 17, 2012, 08:04 PM
I deal in reality
Here's how a detector works. It transmitts out a signal at a fixed strength. It then measures the strength of the return signal. SO, the larger the metal object, the further away it will be picked up. If you have a pot of gold coins, it will pick up that mass of coins. I would try a 2 Box detector. Most will go over 6' for a pot of gold coins. You can probably pick one up on E Bay for around $300. The old Transistor models are as good as the new ones. Don't get an old tube model. I use the Hays, but most are good if in good working condition. The Lorenz PI is a good unit, but pricy, as I recall, it is in 4digit territory. In clay, you could just use a rod to probe if you have a good location. I also go along with the member that said those stories are a dime a dozen or words to that effect.
Last edited by Frankn; Aug 08, 2012 at 04:43 PM.
Jul 17, 2012, 08:33 PM
A clay pot if its full of coins will register approx the size of the diameter of the pot or container. At 2-4 ft we just use our White 808 two box. We work in highly mineralized soil and the 808 can be dialed down to pretty much ignore the mineralization. Hope you find your cache.
Jul 17, 2012, 09:10 PM
Has anyone here used a Minelab GPX 5000 with a big coil besides me? Where are my GPX people? Soil does not get any more mineralized than that found in the goldfields of Arizona and Australia. If it is a cache of coins in a clay pot, the Minelab will hit it at 40-inches like it was a truck bumper.
Jul 17, 2012, 09:12 PM
Gosh, a salesman talking out of his belly-button.. Who would have thunk it?
Originally Posted by mbryant01
Jul 17, 2012, 09:26 PM
You might have misunderstood. Sure, loose coins are not going to hit as hard (or discriminate as well) as a solid object of the same weight.
Originally Posted by mbryant01
Just an example I dug a 36 inch deep hole and poured a hundred copper pennies in it. So that's about a handful of coins spread out over the six inch diameter. The 18 inch coil detected them. Now I am fairly certain one penny would not have been detected.
Jul 18, 2012, 12:07 AM
what hath god wrought
It's the enigma of metal detecting. You can find a cache so easy, it's so simple a caveman could do it. But you have trash. Now you cant do it. Now two to four feet, no way, unless it is trash free. A two box would make this almost easy enough for even a cave man to find. Two to four feet deep, you cant miss it and you wont dig shallow trash.
Federal Bureau of Governmental Redundancy Reduction Agency
Jul 18, 2012, 09:39 AM
I owned a two-box. Like that one thread about which detector do you dislike, the two-box is on the top of my dislike list. I sent mine into to the factory for re-tuning. They said it was "good as new". Maybe they are okay in no mineralization, but what I found was it was worthless as a cache machine for my area. A garbage can lid at three feet? Probably, but you can't depend on that if there are any factors involved like mineralization or power lines within a couple hundred feet. They work good in air test. The two-bow were originally never advertised as a treasure hunter. They always were classified as an "industrial locator" meaning things like septic tanks, etc. I chuckled what one guy said about finding a car body at four feet. He said a VW only two and a half feet.
Jul 18, 2012, 02:09 PM
I get it now. Thanks for the info. I'm going to check out the Golden Sense detector made by Nokta or a PI unit.
Jul 18, 2012, 03:09 PM
I don't know much about the Golden sense but it is a VLF and VLF's do not work that well in mineralized ground. I read somewhere they only go that extreme depth if you adjust the ground balance so far over. But I've never used one and don't know. You might want to do some research on that one. The post I read said the guy only got nine inches until he tweaked it way out. That doesn't mean it will work in the real world or in mineralized ground. Again, I don't know. I do know pulse with a big coil will work in mineralized ground.
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