Looking for an ancient, buried stream bed likely to have black sand and gold

[Rob in KS]

I've been chatting with a guy that has developed a magnetometer. He is looking for a place to test it. I can't help him from Kansas. I bet somebody here can help. Yes, I told him about T-net. Maybe he'll join us here.

Here is his message
I've been busy customizing and outfitting a recently purchased Aliner pop-up camper, but have not been having much luck finding suitable locations and participants for locating and digging ancient, buried stream channels. Perhaps there might be some interest from your mostly-metal-detector group (Mountain time zone states preferred.)

Of course, my participation would be entirely at my expense -- but I would like to keep anything that I personally dig and process.

 

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[Goldwasher]

oh the way I read it was that the pop up was turned into the magnatometermajjiger

 

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[Goldwasher]

Only six to eight feet?

A gold pan and prospector can find that.

A shovel can work it?

I'm missing the leap in detecting ability here?

Buried channels that shallow are relatively easy to find.

 

[Clay Diggins]

I personally stay far away from any system claiming to provide 3D information from a lineal surface scan. Smells like fake science.

BillA makes some good points. I would add that the presence or absence of magnetite is not an indicator of subsurface gold deposits whether in situ or placer. Iron is one of the most common metal in the earth's surface, about 5% of the crust. Gold is one of the least common, about 0.0000011% of the earths crust. Gold deposits are not always associated with magnetite and magnetite deposits are only very rarely associated with gold.

The deserts of the southwest United States are full of washes loaded with black iron based magnetic sands. These magnetic sand deposits form threads and pockets on the surface and at depth from physical sorting processes such as wind, earth movement and in some cases water. These washes are the norm, it's extremely rare to find a wash without large quantities of black magnetic sands. It's also rare to find gold associated with those black magnetic sands. Prospecting in these deserts where the minerals are exposed to view it quickly becomes evident that although gold is sometimes associated with black sands the mere presence of magnetite in no way indicates the presence of gold or any other mineral other than iron.

It's not uncommon to find gold in proximity to magnetite. It's even more common to find gold in proximity to silica minerals. Neither iron nor silica minerals are an indicator of gold. More closely associated with gold deposits are copper and silver minerals although gold is also rare in those deposits.

Metal detectors are particularly suited to locating concentrations of conductive minerals like iron, copper and silver in a specific small area. Metal detectors also detect non magnetic iron minerals - unlike magnetometers. Metal detectors are also very good at finding gold by the same method. Magnetometers do not detect gold, copper, silver or other non magnetic iron minerals, they only detect concentrations of magnetic iron.

Magnetometers do have a place in prospecting. They are specifically useful for finding magnetic iron. To the best of my knowledge magnetometers detect nothing but concentrations of magnetic iron. Iron prospectors use aerial magnetometers to help them define where the heaviest concentrations of magnetic iron are located. Of course they are also prospecting for non magnetic iron deposits, magnetometers can not detect those iron deposits so even iron prospectors have to resort to other prospecting methods to define a deposit worth mining.

Heavy Pans

 

[Don Land]

Some TopoMag Answers

Hello Bill,
My two TopoMag systems are single sensor proton precession magnetometers, and have no way to sense and log the depth of a target -- only the relative intensity, which is stored and displayed in both 2D and 3D form. The TopoMag PC software is a specialized version of my MagSurvey software as you saw on MagSurvey.com.

Yes, proper readings would be obscured if encountering a buried field of steel "tin" cans. However known-faulty readings can be individually erased on screen.

For best operation of TopoMag, a second person would carry the bluetooth-connected tablet PC from 8 to 15 feet away (to reduce interference), and mid-day surveys would be avoided because possible sun-spot interference would be most likely at that time of day.

I have designed and built several unique versions of pulse induction metal detectors for underwater use -- but even my bulky, purchased, Pulse8X does not have anywhere near the range that a proton mag has for detecting black magnetite. (I don't believe any PI unit can even come near.) I don't think a combo unit would be an advantage -- for one thing, a PI sensor needs to be close to the ground for maximum range, but a mag sensor should be at least 30" above ground to avoid the interference of parasitic ground currents.

Perfect? -- No -- but how else might you find ancient, buried stream channels without digging the whole field (as Goldwasher would do)!
Don

 

[BillA]

Don, my PI comments were intended as a joke
some suggestions off the top of my head (very costly experience)
- set up a single sensor fixed recording station at the edge of your grid so that you specifically know what the actual diurnal correction is for each reading (will reduce the uncertainty associated with every reading, worthwhile)
- add a second sensor (normally above), the work is walking the traverses where more sensors = data to crunch
- add a third sensor (offset, lead, lag, ??) and deal with the resulting data streams - fascinating to consider, I never did such

rig up a portable datalogger with as much GPS as you can afford (2 people with a laptop won't fly), process later

put your best foot forward, you are selling to skeptics
Bill

 

[Don Land]

Hello Bill,
Sorry for the confusion about the 3D display function -- I introduced the MagSurvey software 18 years ago, and the 3D display was my way to present both positive and negative anomalies in an informative layout (typically shipwreck material across the sea floor).

Instead of recording all readings, only the most positive and most negative readings are stored for each "map element", and the displays are instantaneous (no post-processing needed, while resulting in small storage files). Depending on the scale used, a map element can be as little as 0.001 minutes latitude (~6 ft) -- somewhat fewer feet in longitude, depending on the survey location on the globe.

Thanks for the suggestions, but I feel that the non-base-station-corrected readings currently used, and the single sensor, will be adequate for the task. (Gotta admit, I am surprised at the cynicism I have encountered on this site.)
Don

 

[BillA]

Hello Bill, . . . . .
(Gotta admit, I am surprised at the cynicism I have encountered on this site.)
Don

older crowd I suspect

 

[dave wiseman]

If you've the time and inclination,read this.......https://archive.org/stream/tertiarygravels00knowgoog/tertiarygravels00knowgoog_djvu.txt

 

[Don Land]

That's a long one -- thanks.
Don

 

[IMAUDIGGER]

So, you are opposed to testing a new concept in placer gold mining, are you imaudigger?

I don't understand where you got that idea.
Simple questions with a couple jokes thrown in.

Knowing the magnitude of the venture you are proposing is helpful.

I would LOVE some new technology or improvement of existing technology that would allow us to be able to dig in the most likely location. There is not always an abundance of hematite/magnetite associated with the gold.

Lack of water, excessive depths, cemented conglomerates, ect. all probably contribute to virgin "ancient" channel deposits. I would think 5-8 feet deep would be considered a shallow placer deposit.

There was a husband/wife team in Alaska that had their claim surveyed. The mapping looked promising, but I seem to recall they didn't have much luck. I don't think they post any updates any longer. I was curious if it ended up being a beneficial thing to have done.

 

[clueless prospector]

Rob, my suggestion would be to contact some of the many gold prospecting clubs across the west. I know there are about 4 n Utah and there was and probably still is one in Ely, Nevada. Most have a webpage or Facebook page. Simply do an internet search and you should find a few. The trick is to convince one or more of them to let you visit their claims without joining the club. Having been a member of multiple clubs and having visited with others, I would be willing to bet that several would welcome the opportunity to share and visit with a fellow prospector.

 

[Clay Diggins]

Why not just prospect open land? No need to use someone's claim. That would certainly prove or disprove your theory and you could keep all the gold you found beenie weenies or not. Lots of open land out there with magnetic black sands, some of it even has gold associated with it.

Heavy Pans

 

[IMAUDIGGER]

Hi Don, I am not speaking for imaudigger but his questions are obvious to a miner - and I know this because I too took a mag 'to find gold'.
You may have a new mag, but mag technology is not new to the goldfields; there are reasons for the limited use.
Your product/services will be successful only if the known deficiencies with existing mag surveys are addressed in some manner.

I took a brief look at your site but did not see what I was after, a topo with the mag survey superimposed showing the depth to magnetite.
Software can generate a spike of any magnitude desired, obviously it is a transverse survey's series of peaks that delineate the course.
Some depth info can extracted depending on the sensor arraignment, are you/your software doing that ?
You are interested in a small portion of the overall magnetic signature, how are you separating the surface (trash) response ?

It is understood that creeks/rivers change their course over time, sometimes slowly and sometimes abruptly (ancient rivers).
Gold can be left behind, is the mag detectable magnetite also left behind in sufficient quantity ?
only sometimes

this is the problem: there can be substantial gold that a mag survey will not disclose due to a (fairly common) lack of magnetite
why not couple a PI and mag ?

edit: Don, if you can make a PI that will detect 100 gm single nugget (or 200 gm) at 6', you could drop the mag

What your after is isopac contours overlaid on a topographical map. Instead of shaded colors representing vegetation, there would be a colored translucent intensity map. Not the easiest for a novice to interpret, but highly useful. I know exactly what it looks like. Not sure enough data is being collected to create an accurate map like this.
EDIT: at 5-8 feet depth the isopac contours would be irrelevant.

 

[BillA]

. . . .
EDIT: at 5-8 feet depth the isopac contours would be irrelevant.

many difficulties in trying to 'edit' the mag reading to disclose the surface (which would certainly include the top 1-8 feet)
quite easy to manipulate, but then the field correlation must be established (dozer and washplant); costly

I did not sell my mags because they were boring, just could not use them to find gold in any reliable sense.

 

[Don Land]

Why not just prospect open land? No need to use someone's claim. That would certainly prove or disprove your theory and you could keep all the gold you found beenie weenies or not. Lots of open land out there with magnetic black sands, some of it even has gold associated with it.

Heavy Pans

Just picking locations at random would not be a meaningful test -- there needs to have been historic gold production in the immediate vicinity for any relevance. As previously stated, the locations could be claimable public land with no active placer claim, or claimed (or private) land with the owner's consent.

 

[Clay Diggins]

Just picking locations at random would not be a meaningful test -- there needs to have been historic gold production in the immediate vicinity for any relevance. As previously stated, the locations could be claimable public land with no active placer claim, or claimed (or private) land with the owner's consent.

I never suggested "locations at random" Don. There are hundreds of acres, open to prospecting with no permit or permission needed within a 20 minute drive of my home with both black magnetic sands and a documented history of producing gold. No need for a mining claim, prospecting club or private land. People prospect for and find gold within this area every day of the year.

You seem to want to discover gold at a location already proven to contain gold? Wouldn't that "test" be very much like taking your friend out to help you bury treasure then seeing how well he can "discover" the buried treasure?

Prospecting for gold is the act of searching mineralized areas for the presence of gold in paying quantities. That's been the job description for many thousands of years. No matter what tools you use that is still the objective today.

If you want to prove your machine's value to prospectors you will need to demonstrate that your method will discover gold in paying quantities from mineralized ground. That is what would make your test meaningful to "cynical" prospectors. Anything less than that and you will quickly lose interest from your potential customer base.

Heavy Pans