"Native" iron, any relation to gold deposits?

[Ed in SoDak]

Hi Steve,

Here's one for you that's been puzzling me for some time. I've been discovering these little patches of so-called native iron on my property and also in a fairly wide area around where I live.

These grade from black sands upwards to slaty bits and larger chunks with a weak magnetic attraction, and also "true iron" slivers and "nuggets" that weigh up into the multi-gram range. I posted a bit about it on another thread in the T2 forum, along with the pic seen below: http://www.findmall.com/read.php?58,1766028,1766887#msg-1766887

There's really nothing I can see on my land to suggest a bench placer, I just seem to fnd a lot of iron around here! I've read where iron and gold are often associated geologically, and not necessarily just in a placer context where heavies naturally concentrate together.

I guess black sands have to come from somewhere. I always thought magnetite didn't become "black sands" till ground down by stream action. Finding that fine of a magnetic grit so frequently in my yard has me scratching my chin in a hopeful way.

Then there's the larger solid metal chunks I find. Some may be "schrapnel" off a dozer blade or logging equipment, but so very few of them appear to have any manmade evidence that I am once again wondering if those are natural, manmade or possibly meteorites.

I have some pretty detailed geologist's and mining engineer's reports for the several historical mines of record that share this gulch, and there is scant to no mention of all this iron.

Most all the mines on this gulch are located along a fault with quartz outcroppings and reports of some native gold within. I also find apparent gossan outcrops of rusty clays and a lot of hole-shot and very rusty-looking quartz, with some clear-to-white quartz in areas.

For the most part the iron is a nuisance detector signal, but then maybe it's also trying to tell me something. What it's saying to me is the part that I'm missing. Any help or experience? I'll ry to get better pics soon.

Thanks!

-Ed

 

[fredm]

If in fact, the larger pieces are free metal you may have an iron-meteorite...there are two tests that MIGHT confirm that...etching for the "widmanstten" pattern and a nickel test done by a reliable lab...drug store nickel tests are unreliable.
www.meteorlab.com was/is offering these tests for a nominal fee...I found them reliable in their actions. I don't have anyway of knowing if their conclusions were correct...but, I don't have any reason to doubt them either.

fred

 

[steve herschbach]

Fred mentioned the meteorite possibilities so I will stick with the main question.

Many primary gold deposits (hardrock or lode) are associated with naturally occuring iron in one form or another. Black sands are a bit different as they are heavy iron minerals that collect along with gold in placer deposits simply because they are heavy. They may have nothing to do with the gold mineralization. But many primary gold deposits are associated with iron sulphides like pyrite or arsenopyrite, or with basic iron ore and ironstone mineralization.

A real eye opener for me in Australia was that I really wanted to chase quartz, but learned soon that it was quartz associated with ironstone that I really wanted. The quartz indicates that mineralized fluids were in motion but it is the ironstone acting as a precipitating agent causing the gold to drop out of solution. So rather than finding nuggets right around the quartz veins it was obvious that the nuggets I was finding were sourcing in banded ironstones.

Gold in ironstone from Australia

What this all means is that the gold in your location may or may not be associated with the ironstones. Since they are detectable, it may be possible to use your detector to try and locate the source of the ironstone just by keeping notes on where you find it. The bottom line for me as a prospector is you have a puzzle piece, and it is nice to find out where all the pieces fit.

Steve Herschbach

 

[Ed in SoDak]

That's a sweet looking rock, Steve! Unfortunately, mine look more like the rock part without the gold thingy. Our rocks have lots of sparklies, which usually end up being mica. They sure catch your eye, though, so we plant 'em along our walkways in the yard.

I gathered up a few views of the samples I've detected. Everything shown reads as iron for ID. Some machines can't read them at all, but are still affected, since these deposits can drag down the ID of good targets that happen to be in their midst.

IronA: First I show the metallics. Shiny surfaces were polished by me. Some may be just busted bits off a skidder or dozer blade, welding or blacksmith's slag, but I'm not totally convinced. I'll have some tested for nickle because I do suspect a few may be meteoritic.

IronB: Next is a closeup of same. Near as I can tell, these are rust-coated, but undecomposed solid iron. Very magnetic, iron ID.

IronC: Then we have detectable iron within or included into quartz rocks. Magnetic enough to stick to one. Iron ID.

IronD: I also find a lot of slaty-irons. These may be banded showing the slate-like layering. Many are brittle and weak enough to break with finger pressure, moreso than the normal slates. These are mildly magnetic and the ID tends to iron but may vary a bit higher. Hard to locate when small.

IronE: Last is the real nuisance iron. Fine bits down to powder. These may not read on a machine that does not have a good no-motion or all-metal mode. ID is generally iron to just above iron. Depth tends to read 6 inches no matter how deep the hole. The target shifts around as you dig and my Falcon pinpointer has a hard time finding any of it. But drag a strong magnet around in the loose dirt, and you can bring up the quantity shown from a 3- or 4-inch hole. Strongly magnetic, considering the fine size. I can locate patches like these all day long. Frustrating, as they somewhat mimic a small nugget signal. They can ID shift a coin or other objects downwards a full denomination in the ID range, depending on the detector. A quarter can read as a dime, dime as a zinc penny, a nickle reads as iron, etc.

I didn't show the rusty clay outcrops or other rusty-looking slates and quartz on the property, but they always catch my eye and sometimes my coil as well. Maybe in a future post I'll shoot some pics to show the various deposits as they look on the ground.

At any rate, they're an interesting curiousity and I try to learn their response so I can better ignore them. OTOH, if there's some geologic association between them and possible gold deposits, i.e., gold in gossan, that's why I'm trying to learn more about them.

I kinda suspect other people have this sort of soil in their area. You read many reports about people who detect "unlocatable" targets or experience odd ID errors. I sugget trying a strong magnet in the hole before blaming the detector as being faulty.

Anyway, on to the pics in the order listed above. Thanks for any observations or insight!
-Ed

 

[cypearl]

Ed I just don't know if you have an answer already but my self found many of those and the most of them are magnetites and hematites. The most common meteorites wrongs. But it is possible you have and a meteorite as well. Now there are some tests you can do at home and they are very easy to do, so search in google for meteorites tests at home and meteorite identification. I hope that helps you.

 

[Ed in SoDak]

Thanks! I haven't done much with these as other projects took over. Getting some of it tested by a lab will be the best answer to my questions. If it leads to gold or a meteorite search, it's all fun either way!

-Ed

 

[Reno Chris]

Part of the confusion in this thread is due to using the term "native iron" to describe Magnetite, hematite, man made trash iron, meteorites, and naturally occuring metallic iron. Native iron is a term which applies only to naturally occuring metallic iron. Black sand is a mixture of iron bearing minerals, but its not metallic iron. Mixing up the terms causes confusion as no one is sure what we are talking about. Here is a brief description for each and the association with natural gold deposits.

Magnetite: naturally occuring iron oxide mineral that is strongly magnetic. Typically black but can have a sort of metallic sheen, but not like true metallic iron. Can definitly be associated with gold in some deposits, but as iron is the 4th most common element in the earth's crust, there is a whole lot of magnetite with no gold associated with it. It occurs in rocks as small partcles, but also as veins and thick beds of solid magnetite.

Hematite: naturally occuring iron oxide mineral that is only very weakly magnetic. Silghtly more oxygen to iron ratio as compared to magnetite. Typically black but can have a sort of metallic sheen, but not like true metallic iron. Can definitly be associated with gold in some deposits, but as iron is the 4th most common element in the earth's crust, there is a whole lot of hematite with no gold associated with it. It occurs in rocks as small partcles, but also as veins and thick beds of solid hematite.

Man-made Trash iron - Metallic iron produced by man. Can definitly be associated with gold as in many places miners camped right on the gold fields and dropped their iron trash all over. Of course there is a whole lot of scrap trash iron not associated with gold.

Meteorites - natural metallic iron that has fallen from space. Always contains significant nickel that made made trash iron rarely has (stainless steel has a significant nickel content). Not associated with gold by any geologic cause, a few placers just by random concidence have meteorites present also.

Native iron - natural metallic iron. does not have significant nickel content. Strongly magnetic as metallic iron nearly always is. Very rare, but some basalts contain blobs of natural metallic iron that re released on erosion. This is the only material which shold be called native iron. It is not associated with gold deposits.

 

[copperkid]

I am currently working on a leached outcrop near Yerington, Nevada and I am finding both native Copper and Native Iron in the deposit. The literature cites that it is very rare in nature but I have also found it associated with gold in the Mariposa Fm. In all cases it is microscopic and extremely magnetic. At first I thought that these pieces were contamination from the crusher so I ground them in a porcelain mortar with the same results.

The native iron may be the result of a reducing pH or, in the case of the Yerington deposit, the weathering of chalcocite in the presence of chalcopyrite. In the California occurrence it is associated with carbonaceous rocks containing over 4% carbon.

If SoDak has spare sample of the native iron, I'd love to look at one. [email subject="native iron"]4us2find@gmail.com[/email]

 

[Ed in SoDak]

I've still just been sitting on these and need to finally find out what they are. I found the first deposits of the fine powdered rusty grits back in 2001 and the first iron "nugget" in 2006. This summer we really added a lot of samples to the pile so I do have a few extras I could send out.

The specimens of any size are not globular, they are more sharp-edged and angular. Going by Reno Chris' post above, that increases the chance they are meteorites. There is basalt in the Hills, but not much if any in the areas I am finding the iron.

Then there's this google earth view that's just down the hillside from where I have found some of the pieces that weigh in the 5+ gram range. Everybody pretty much thinks I'm seeing things, but it sure looks like a pair of small craters to me.

-Ed

 

[kahlesmilcon]

You need to plot your finds around the locations of the "craters"

Sample the quadrants and plot the finds.
The plot will tell you the direction of the hit and also tell you where to look for more of the fragments.

After which then search as you like for more fragments.

If you find gold , don't tell anyone , just smile and keep looking.
If No gold, get in touch with the State college and give them research rights., Possible discount on property taxes? Just saying... you have to think of all of the angles.
Ken

 

[Ed in SoDak]

Well, I sent samples to New England Meteoritical from the link that Fred posted above. $15 covers the cost of testing and return mail for three small pieces, so that's what I sent. After a couple weeks, the samples were returned unaltered with a negative report. They called them ore slag. I don't know what tests were conducted that did not include any physical or chemical tests, so it must have been microscopic or perhaps laser examination only. I don't know one way or the other how accurate their assessment is.

Meanwhile, on the iron issue, a Canadian firm is currently conducting aeromagnetic surveys of the Rochford District that is west and north of me. We kinda border this mining district and the company is apparently also checking where I live, with several daily flyovers pretty much directly overhead. They are tracking and plotting the iron deposits of the area with the intent of relating them to any gold deposits.

So I guess I was onto something after all with my curiousity about the iron. I'm going to gather some more samples and have them tested.

-Ed

 

[jamesinwesttexas]

Ed, I sent a sample to the same place and then to one in Arizona. Neither place sent me what I thought would be a lab analysis, especially a nickle test. I got the impression they just looked at it and sent me their best guess. Until you [or I] get a nickle test done [I'm not sure where to get it] we can't be reasonably sure if we have a meteorite. As for the widmanstatten pattern, that depends on the nickle content and iron meteorites fall into about 3 categories there and the categorie with the lowest nickle content won't show a well defined widmanstatten pattern, but if yours is high in nickle it could, so saw it and polish it I did that to mine and thought I could see a weak pattern. Good luck.

 

[Ed in SoDak]

Thanks James,

Time was I coulda just mailed these to Richard Norton, and his opinion I would have trusted beyond reproach. Now, I don't know of the best place to mail a few small samples. To myself, I think I'm finding the solid irons too broadly distributed to all be manmade, though some by all probabilities are manmade, just by their proximity to known old mining communities, even if the place they were recovered seemed off the beaten path. My finds are all small in size, but the largest (13 grams and under) have all found nearest to my "pet" ancient crater. I'd love for my find to be extraterrestrial, but given the renewed interest in iron associations with gold in this vicinity, I'd be happy with any classification that takes this stuff out of the "nuisance" category. I was actually looking for gold in all these places that I'm primarily finding these weird iron signals.

To my own uneducated observations, I think I'm chasing at least three or four distinct types of iron deposits. Two types contain solid iron, the others probably incorporate magnetite somewhere in their composition. "Real" native iron, in an undecomposed state is perhaps too rare to expect to find it here. So it's either manmade, meteoritic or something else that is unexpected and apparently not following "the rules."

With the aerial magnetic surveying going on, it only makes me all the more curious.

The weather here has been so mild and dry lately, I think I could do some sampling several months early, there's no ground frost to speak of on the hillsides that are in sun.

-Ed

 

[fredm]

Hi Ed;
my report from them says they used a petrology microscope to look for structure and also tested for NI-nickel-...that satisfied me for my 15$...they also suggested the Smithsonian and the Johnson Space center for additional tests...

By the way I believe it is the meteorites with nickel content above 13% that will not have a discernible W-pattern...ataxites...

fred