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[Gregory Yount]

I have a breccia pipe mining claim in Nothern Arizona for which I will be undergoing a validity exam in the next few months. The target has been shown to have a large uranium deposit at depth from a Soil Gas Hydrocarbon survey and analysis.

The surface contours of the land does not scream that there is a pipe structure present, but the fact that there were thousands of goethite pseudomorphs after pyrites (both large and very small) littering the ground and anthills made me very interested. I also had a high uranium soil sample nearby from a comparative geochem survey that I was doing for another breccia pipe target. The surface rock is Kaibab Limestone and this goes down 400 to 500 ft or so.

Mineralized solution collapsed breccia pipes have a massive pyrite cap above the polymetallic ore body and I feel that the goethite pseudomorphs are a weathering out of an extension to the surface of this pyritic structure. The principle ores in the breccia pipes are uranium and copper. There can also be enrichments of Ag, V, Ni, Mo, Pb, and Zn. Some of these elements occur with economic concentrations.

I need to connect the high "trace element" concentrations to the ore concentrations at depth.
Normally, few pipes have any mineral expression from the buried ore bodies at the surface. Having any kind of mineralization or radioactivity on the surface is rare.

The goethites have high values of Vanadium 455ppm, Ag 6.06ppm, Mo 263ppm
and U 21ppm. These values are really high and compare favorably and sometimes higher than values found in actual ore from some of the breccia pipe mines (the V and Mo values).

I need to be able to connect these values and their genesis to the ore down below. I need some scientific references that might explain how the trace elements in the goethites got in there either from being in the pyrites originally when formed or were part of some replacement regime when the pyrites was altered.

I need to know what trace elements might normally be present and expected in goethite pseudomorphs.

Any help would be appreciated.

[Cesar M. Salvan]

did you check K.J. Wenrich, Econ Geol, 80: 1722-1735 (1985) and references therein?

[Les Presmyk]

I cannot help you with the geochemistry you are looking for but can help with either mining engineering or an interest in specimens from Arizona.

[GneissWare]

If you really want a person who knows ore genesis and geochemistry, look up Stan Keith at MagmaChem Exploration, Inc. in Sonoita, Arizona. He probably isn't cheap, but he has been doing trace element geochemistry markers for ore deposits for over 20 years. Google the company name.

[Les Presmyk]

Dr. Jan Rasmussen worked with Stan for a number of years and can help you get in touch with him. She can be reached at 602-771-1612.

[Gregory Yount]

No, I have not found that particular paper. If you have access to it or it is available on the web, I would appreciate a copy or a link. I have read many of the papers written by Karen Wenrich and have actually hired her to help in this matter. To reduce costs to me I am trying to find relevant scientific papers that would address these questions.

Both goethites and pyrites are good scavangers of many metals that are in solution.

I have found a scientific paper that was investigating the dating of Meteor Crater in Arizona by the Uranium and Thorium uptake in oxidized Meteoric iron. The meteoric iron has a really low and relatively known amount of uranium to start with and so comparing the amount of uranium isotopes and thorium and decay products they analysed and made a prediction of the age of the impact crater that fairly well agreed with other dating methods.

Using the midrange of their rate of uptake at: 56,000yrs / 238ppb U I find an approximate time for my goethites of 4.9 millions years to uptake 21,000ppb of uranium.

My question is, is it reasonable that the pyrites in place had no uranium in them and that the pyrites transformed into goethites more that 5 million years ago, remained in place near the surface and took up 21,000 ppb of uranium from surface or near surface solutions of uranium in water?

If the pyrites will oxidize in to goethites in 10,000 or 100,000 years near the surface, then there is no way the gothites tookup that much uranium as has been found in them.

I will also be taking some samples of goethites (if they are to be found) over barren breccia pipes when I am able to get the GPS coordinates of some pipes that were drilled and found barren of U.

Comments??

Greg

[alfredo]

Why would goethites be limited to taking up uranium (or any other element) at such a slow rate? I would think they could adsorb some elements like U, V, As, etc extremely rapidly, depending on quantity present in solution in soil water, degree of division of the goethite particles, perhaps also ambient temperature, or even the plant species present, or any number of other variables. No reason I can think of that the uptake rate couldn't be orders of magnitude different than what was measured in Canon Diablo oxide crusts.

[Gregory Yount]

What you are saying is true. There are a lot of variables. The dating study was the only study that I could find that studies the uptake of U on a macro size piece of iron/goethite in a natural setting.

Very finely ground or manufactured goethite will takeup Uranium in a matter of hours in a "test tube" due to the scavanging effeciency of the mineral and to the large surface area created by the finey divided goethite.

The Canyon Diablo area is a similar geologic area as to the Breccia Pipe provence. The soils in the area that I have tested (South of the Grand Canyon) have 1.5 to 3 ppm U and I extended that level to the Diablo Canyon area.

So, given that I am dealing with goethites pseudomorphs in size from 1mm to 3cm, I used the Meteor Crater study as the closest in similarity to my situation. It is the best I can do for now.

If you know of any studies or references that might be better, please pass them along.

Greg

[Peter Megaw]

Dave Jones did a lot of very good, systematic exploration for these breccia pipes 30 years ago for Noranda and probably knows them better than most geologists... I would recommend you contact him directly jdavidm243(at)aol(dot)com since he is not a mineral collector. He is available as a consultant. I'd be happy to directly discuss his credentials relative to the others mentioned.

"Limonite Dice" are not uncommon in many sedimentary rocks and as you've mentioned they may have scavenged metals from the environment. That said, those metals must be present to have been scavenged, so it still suggests you're in/near the right place. So, your basic story of a link between the pseudos and a pipe seems plausible enough that only a rotary truth machine (drill rig) will tell. Question is...who pays for it?

[Ed Huskinson]

Rotary Truth Machine!!! You crack me up Pedro....

[Peter Megaw]

Also heard it called a "rotary lie detector"

[alfredo]

Is that related to Mark Twain's definition of a "mine": a hole in the ground with a liar standing on top?

[Peter Megaw]

Roughing It should be required reading for anyone with anything to do with mining

[zar24]

Dear Gregory

Hi

Please look at this Link ( https://www.mineral-forum.com/message-board/viewtopic.php?t=3480 ).

What is your Idea? are these minerals same as yours?

Tell me about your ultimate findings. does it have any worth?
Share your finding please.

Thank you

Zargham