Do You Consider Your Soil Highly Mineralized And Where?

[Skookum]

I’m curious to how you all see the mineralization of the soils you detect compared to other locations. Our soil here in central Arizona seems to be fairly mineralized. But, we haven’t been detecting anywhere out of state to let us effectively compare. Here’s a USGS map showing relative iron concentration in US soils. There appears to be heavy iron concentrations in the Pacific Northwest.  Does this reflect your experience on the ground?  If so, has this affected what you choose to swing?  If not, how do you think your soil compares to elsewhere?

us iron concentrations.pdf

[AllenJ]

I'm in Northern California and yes, that is my experience up here.  Our soil is all over the place, to the point that VLF's can be pretty much useless in certain areas due to mineralization.  I ended up getting a PI and the difference was unbelievable.  The PI won't see small gold nearly as good as the VLF but at least you're looking for gold and not digging up hot rocks and ghost signals!

[Skookum]

Thanks for the response.  I’ve been wondering how Arizona compares to elsewhere.  We don't have crazy red dirt all over here like I see in some photos of Australia, but it seems we have a lot of hot rocks.  Anybody here with experience in Arizona vs. other states?

[Gerry in Idaho]

Interesting read.  I would say my gold hunting areas in Idaho are mostly mild, but I do have some hot areas.  Eastern Oregon were I hunt is more mineralized than my South Idaho sites.  The ground I swing in Northern Nevada is actually pretty mild, but I do know of a few hot areas.  When I head to Montana, I feel the sites I hunt there have the hottest ground of all.  Yes I feel MT is hotter than the areas I swing in Arizona too.  

[klunker]

 

On 7/8/2019 at 9:24 AM, AllenJ said:

Our soil is all over the place,

 There is so dang much that happened gee oh lodge iklee in the Northern Sierras that in a days worth of detecting you could run across a dozen different rock and soil types. Ya just do the best you can with what ya got. There are some spots where the ground is so mineralized with gold that you can't get a detector to run quietly no matter what you do. It could drive you crazy- as it did me.

[fredmason]

Klunker

we should all suffer from so much gold under the coil that our detectors will not ground-balance...poor thing!

fred

[klunker]

7 hours ago, fredmason said:

we should all suffer from so much gold under the coil that our detectors will not ground-balance

Well Fred, I don't recall weather it really happened or it's just my imagination, but you know with me it's all the same.

[Skookum]

Any idea how Nevada compares to Arizona (in general)?

[GB_Amateur]

Here's the original paper:  https://pubs.usgs.gov/pp/1270/pdf/PP1270_508.pdf

It's worth noting that the map shows iron concentrations totalled over all chemical forms, not just the insidious (to detectorists and other gold recoverers) magnetite.

From Wikipedia:  https://en.wikipedia.org/wiki/Iron_ore

Although iron is the fourth-most abundant element in the Earth's crust, comprising about 5%, the vast majority is bound in silicate or more rarely carbonate minerals (for more information, see iron cycle). The thermodynamic barriers to separating pure iron from these minerals are formidable and energy intensive, therefore all sources of iron used by human industry exploit comparatively rarer iron oxide minerals, primarily hematite.

Thus magnetite isn't even the most abundant oxide of iron.  (Hematite is only weakly ferromagnetic.  See: https://en.wikipedia.org/wiki/Hematite#Magnetism)

I bring all this up because the Fe3O4 (magnetite) scales on the Fisher F75 and Fisher Gold Bug show iron concentrations considerably less (by roughly a factor of 10) than those in the map Skokum included above.  The detectors actually measure magnetic susceptibility but the results are reported in Fe3O4 equivalent units. (See:

http://www.fisherlab.com/hobby/davejohnson/DavesGoldbook-reders.pdf

especially pages 12-13 and 24-26.)

 

 

[Steve Herschbach]

On 7/13/2019 at 7:24 PM, Skookum said:

Any idea how Nevada compares to Arizona (in general)?

In general lower than AZ but that really does not mean anything. I have been in low mineral ground here and moved a mile and been in bad hot rocks. It simply depends exactly where you are. People also forget salt mineralization can mess you up even more than magnetic sand and plenty of NV locations are loaded with salt. Ok when bone dry and near undetectable when wet.