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Where does gold come from? with AZ Nugget Bob...


AzNuggetBob

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Hey all, I'm back. I've been real sick for the about last month. but I'm feelin better. long story. anyway, So I'll be answering questions again if I can.
Rim I agree its hard to find detailed information in most books (with photos)on the minerals to look for when prospecting/detecting or gold nuggets. also most are photos of these minerals in pristine condition (as formed in hard rock) not what they look like after being ground down or oxidized in placers or laid out on hillsides for thousands of years. I was going to write my version of a book on this but I think I'm just going to share it. just give me a little time to reply and I'll tell you what has worked well for me over the years with a detector and how I learned to track down pounds of those gold nuggets and patches. Please keep in mind this a pinned post, so Cut down on the pure bs stories, but jokes, jabs and your own experiences/stories are welcome.
AzNuggetBob

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Welcome back Bob ... figured something was up but didn't know what ... thought maybe you were out in the field on an extended wilderness hunt. Glad to hear you are feeling better.

Mike F

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Welcome back AzNuggetBob! Glad you're feeling better. I enjoy your stories greatly. They keep my motivation rushing high. And your willingness to share information to the newcomers is greatly appreciated.

I agree with Rim that it is really difficult to picture the types of .. country rock, zone alterations ... etc.

Now to get to a question for Jim, Bill, AzNBob or others in the know: I spend a lot of time in AZ in the LSD areas where gold has been found before. I will be working in iron rich red dirt areas and come across large areas that turn bleach white. I don't know if this is an alteration zone or some other enrichment process that might be one more clue to possible hillside nuggets. Next time out I will get pictures to describe this better. Nearby the area that is bleach white are large basalt protrusions and bull float .. which doesnt excite me too much. But the color change makes me wonder what did this. Would this kind of areas be of interest for hillside detecting? And if so ... would you detect inside this area or outide of it?

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Welcome back AzNuggetBob! Glad you're feeling better. I enjoy your stories greatly. They keep my motivation rushing high. And your willingness to share information to the newcomers is greatly appreciated.

I agree with Rim that it is really difficult to picture the types of .. country rock, zone alterations ... etc.

Now to get to a question for Jim, Bill, AzNBob or others in the know: I spend a lot of time in AZ in the LSD areas where gold has been found before. I will be working in iron rich red dirt areas and come across large areas that turn bleach white. I don't know if this is an alteration zone or some other enrichment process that might be one more clue to possible hillside nuggets. Next time out I will get pictures to describe this better. Nearby the area that is bleach white are large basalt protrusions and bull float .. which doesnt excite me too much. But the color change makes me wonder what did this. Would this kind of areas be of interest for hillside detecting? And if so ... would you detect inside this area or outide of it?

Thanks guys

Andyy

I'm was going to discuss looking for indicators, so may as well start here. I think I know what you are referring too as I see this in some other areas too. Quartzite, W. Nevada etc is a good example of this also. I tend to look for mineralized spots in a given area. anything from high iron (red) spots, areas to dark brown or even black. any stand out spots can indicate a high mineralized outcrop or a placer concentration (rusting magnetic black sand). but in some areas as mentioned the soil can be bleached, oxidized having been rinsed over hundreds of thousands of years washing away mineralization causing the staining or it can be covered in high alkaline soil on the surface overlain by soil from above the mineralized zone covering it up with calcium/ lime blowing in the wind. sometimes I look for it bleeding out along the edges of ridges with well rounded hematite, magnetite or even limonite nuggets bleeding out with quartz float. sometimes I will dig a small test hole if I just suspect its there. with practice running your detector in fixed mode can also help indicate hidden hot spots or areas. I found many areas where rhere was nothing was left but white bull quartz and smooth gold nuggets. almost no staining at all. (Nev)

Some of these are very old placers and appear to have been created and/or covered up at least in part by several major flooding events and erosion by gravity separation in more recent times. on these I'm always keeping an eye out looking for well rounded gravels, very old boulder runs lining up on ridges and hillsides by rivers and streams changing course abandoning them high up off the present day valley floor. some of these deposits are so old,the rocks or pebbles rotted and decomposed in place. these well rounded cobbles that at one time survived major flooding just crush in your hand. other rocks in them that survived these floods and time were chert, chalcedony,diorite, jasper,rhyolite and flint that the Indians used to flake into arrowheads.

Hey nugget108

I saw the gold species you have been finding on another thread, Very Nice and the fact you got the claims is a real plus too.

best of luck on more.

The rock seems to be stable enough to cab for jewlery,have you considered slicing some up with a rock saw.

AzNuggetBob

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Lets talk about erosion. here is one type that most people don't even think about. have you ever seen granite boulders that have a skin popped off like an orange peel. still laying on top or fallen to the side? this is caused by rain and freezing. yep granite is porous not unlike many other types of rock. when it rains the water soaks in and if it freezes it POPs. freezing from expansion is very powerful, it can burst steel water pipes, sometimes the rock will jump off the boulder or lay there until later, it cracks more and is blown or washed off from rain. if you've been out in freezing weather in granite areas you probably have heard this and wondered where those pops came from. If the boulder has veins like quartz veins or stringers the water can soak down into the crack between the two rock types and split the whole boulder when it freezes. if there happens to be gold in that stringer or vein a gold nugget is born.
AzNuggetBob

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Also, besides freeze/thaw erosion, there's the process of exfoliation which looks similar only on a larger scale. It's due to expansion of the rock as overburden is eroded away and the latent pressure inside the rock (( it formed with a couple (or more) miles of country rock over it's head )) is able to be released.

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Bob ... excellent explanation of the erosion process on granite. As a life long resident until a few years ago I witnessed that in any number of places particularly in Maine and NH (the Granite State). I would be out hunting deer after a cold rain and then hard freeze and would on occasion hear that popping you talk about. It is not real loud as one might expect but a very definite 'POP' if standing nearby.

Mike F

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Your correct Weaver Hillbille, heating expansion is also a common form of erosion, weathering. there are many types of erosion, even roots from trees will split the bedrock. its all part of the process.

Hey Mike, things that go bump in the night. :yikes::D your right it's not that loud but once you learn what it sounds like youll hear it more often.
its sort of a low pop and if you happen to be close enough to it when it happens you can feel it through the ground.
The reason I'm referring to granite in particular is its often in the area where I'm hunting gold nuggets. but this form of erosion/weathering happens with other types of rock too.

Here is another type of erosion I have personally witnessed. one time I was laying in my GI jungle hammock up in the Prescott Az. area just looking out the mosquito netting waiting for the rain to quit, just staring at the boulders and pondering where all the gold is and all of a sudden BLAM! a lighting strike hits up on the ridge near me. I look up on the ridge and this granite outcrop is smoking steam! later I hiked up there to see it up close and the lightning had popped a wedge shaped chunk out of the bedrock about 4' long by 3' thick. nice fresh clean broken granite. I'll never forget it also had a very strange smell. it looked like it jumped straight up and came down in the same spot almost upside down. I had seen these formations in other areas and thought someone had pried them up with a bar or something?
mystery solved.
I had a photo of one these, If I find it I'll put it up here.
AzNuggetBob

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AznuggetBob- thank you for your thoughts on the bleaching. Gives me some things to think about. It seems erosion takes on many complex forms.

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Andyy
Here is more on the San Domingo area. I kind of got off on rant describing Nev. on my last reply to you as they are similar. here is a little more info on that area specifically.The San Domingo area has more thick larger well defined quartz veins with as I recall a N.E. trend. most of the gold reported in that main wash and area came from them. its surprising that there's not more written about it considering how much gold came out of the main wash and tribs.
But as you move over toward the little San Domingo area the veins become less well defined with more small random veins and lots of quartz stringers. the deposits are secondary deposits as discussed earlier in this thread. Many only producing a few grams to a few ounces of gold and only rich at the surface. being small outcrops, they can be difficult to see at a distance. and because there are so many small washes and tributaries in that area you almost have to be standing right on top of the smaller outcrops to see them. some of the gold nugget deposits are shallow and then run deep down on the lower reaches of those gulches and small gullies but that's what makes the area impossible to hunt out. down lower you'll find those old cemented gravels (conglomerates) also sometimes called caliche or false bedrock. this is the source of much of the alkali that's blowing around up there. If you get to high on the mountains there its volcanic, possibly an old magma pipe, and Ive never found any gold up there. Hope this helps, AzNuggetBob

Edited by AzNuggetBob
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That's very interestingn AZNBob. True the stringer I have found do have a NE trend which I found to be strange since the geological maps show that the schist pattern took an approx NE direction. Along with the directional tendency of faults. Yet trying to follow quartz towards a contact zone is above my knowledge at this point. Hard to know what to look for without seeing examples. But I know this is a good thing based on what i've studied from your other threads. But getting back to the smaller stringers, I understand that this also slows down the cooling and separation of gold and might lead to larger nuggets. Ive know of people pulling 1oz nuggets from the hillsides in the area but not sure whether this was closer to th LSD side or the main San Domingo wash. I understood there was probably higher qty near the main wash but the LSD tributaries might carry larger nuggets. Maybe this is due to the stringer size. Your caliche comment is interesting because this is where the dry washers seem to focus on in this area. Me, i'm trying to get a better understanding on geology for only metal detecting. Ill scan the sides of the washes where the dry washers focus and the piles of course but I have not had a lot of luck. Everybody hits these washes but hillside detecting really seems to be an art that requires a lot of patience and geological understanding and vision. These are the pictures I am trying to build in my goldhunting101 mind.

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Andyy

This forum is loaded with great info and links on finding gold. I know gold hunters that are finding gold almost every time they go out hunting,and they spend a lot of time doing research too. All you have to do is take the time to learn where to look and how to find it. but It can also take a lot more time with research and testing to confirm the sources of the gold. AzNuggetBob

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Let me explain this with more detail. I'm confident most all the gold there was formed there during one or more volcanic period(s). Iron mixed with hot volcanic solutions can produce acidity deep below in the earths crust and lower mantle. these high temp acidic solutions percolate and leach, dissolving finely divided gold from the surrounding bedrock . If these are under the ocean hydrothermal or geothermal vents and are acidic and they will carry micron size metals up with them in the hot solution.
Two things that are very good at dropping or releasing metal back out of solution and redepositing are lower temperature and alkalinity. it neutralizes the acidity raising the PH above where the gold can remain in solution and allows it to combine into larger particles that can no longer float in the solutions. their may even be some electrolysis going on too from lightning storms caused by the volcanic clouds? but that's just a theory of mine. but this would also explain the surface only pockets that area is known for.
So when this metal rich solution comes up and hits the cold alkaline ocean water (smokers)or even the alkaline rich caliche on the surface, BOOM the gold precipitates out and falls back down to the ocean floor or deposits right at the ground surface by evaporation along the faults,quartz veins,vugs and stringers if on dry land. its a natural volcanic steam powered plumbing network.
Another thing is you don't want to hunt to close to the main volcanic vents. I think it was to hot for any gold rich solutions to percolate below and were driven to the sides by the heat from the magma or they just instantly vaporized into clouds and exited up the main vent and out into the air in the form of steam and smoke with nothing to stop or precipitate it out. you could say, gone with the wind. a slow perc is better than a single catastrophic event.
So the key is to hunt the perimeter of these big main volcanic vents. to close, its to hot. to far away, no more surface volcanic activity. the distance seems to depend on the size of the main vent.
AzNuggetBob

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Thanks AzNuggetBob!

Based on the info (that is the info that's sunk into my thick skull) you've shared in this topic, I have an educated guess as where to detect for my first nugget. It's a flat bench about 1 to 2 feet thick on the inside bend near several large quartz veins. I found two pickers under a rounded boulder- with my vaccum-next to the edge of the wash. I haven't hiked up the hill yet. There are mines in the area. All I have to do is wait for the desert oven to cool down a bit.

Or sleep in the freezer the night before then drive like a bat outta hell... :nutty:

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Thanks AzNuggetBob!

Based on the info (that is the info that's sunk into my thick skull) you've shared in this topic, I have an educated guess as where to detect for my first nugget. It's a flat bench about 1 to 2 feet thick on the inside bend near several large quartz veins. I found two pickers under a rounded boulder- with my vaccum-next to the edge of the wash. I haven't hiked up the hill yet. There are mines in the area. All I have to do is wait for the desert oven to cool down a bit.

Or sleep in the freezer the night before then drive like a bat outta hell... :nutty:

Ya I agree AZMark

Its gettin smokin hot out there. and your not far off in your idea but your joke was funny. :D

If it gets any hotter I may have to get one of these.

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CEkQFjAA&url=http%3A%2F%2Fwww.veskimo.com%2Fwhy-best-cooling-vest.php&ei=piWDVYThOoOvggTzh6OgCg&usg=AFQjCNHO2qBb0KDFDo4EpaLQMhWJxuD24Q&bvm=bv.96041959,d.eXY

but for now one of the things I use to help stay cool is by freezing my Hydration Backpack the night before hunting. just being up against my back helps keep me cooler and the cool water for drinking is always a plus.

Note: stand your Hydration back pack up in the freezer with the fill cap loose and not completely full of water, remember the freezing expansion thing. and then I top it off with water just before I leave. and dont forget to carry lots of water in your rig too. even warm water is better than no water.

Take care out there, AzNuggetBob

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Thank 's Bill, I'm having a lot of fun here and appreciate all the positive comments. I'm just sharing ideas on detecting and prospecting that have worked for me.
ya I change topics often.
but sometimes people make a comment that reminds me of something I think is an important topic that I can share something I've learned that may help make their next prospecting adventure more fun and be more successful too.
AzNuggetBob

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Ya I agree AZMark

Its gettin smokin hot out there. and your not far off in your idea but your joke was funny. :D

If it gets any hotter I may have to get one of these.

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CEkQFjAA&url=http%3A%2F%2Fwww.veskimo.com%2Fwhy-best-cooling-vest.php&ei=piWDVYThOoOvggTzh6OgCg&usg=AFQjCNHO2qBb0KDFDo4EpaLQMhWJxuD24Q&bvm=bv.96041959,d.eXY

but for now one of the things I use to help stay cool is by freezing my Hydration Backpack the night before hunting. just being up against my back helps keep me cooler and the cool water for drinking is always a plus.

Note: stand your Hydration back pack up in the freezer with the fill cap loose and not completely full of water, remember the freezing expansion thing. and then I top it off with water just before I leave. and dont forget to carry lots of water in your rig too. even warm water is better than no water.

Take care out there, AzNuggetBob

Ice Tea stays frozen longer then water. I don't use sugar.

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Yes, AZMark is a funny guy :-)

As for surviving the heat, frozen canteens mixed with a little gatorade helped me through my forest service stint. AzNuggetBob has it right though .. leave a good amount of space at the top.

Still, its too hot for me. I'm taking this time to try and learn up for the fall. Or maybe an occasional night hunt utilizing snake chaps.

And thanks again for the great information AzNuggetBob.

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I'm trying to decide if this is a trick question. With 800 posts and the name GeoJack, I am guessing that I should be sending pictures to you. :4chsmu1:

This would be a good topic ... name that mineral.

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