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Gold And Geology Sharing What You Have Learned


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 I wanted to start this thread because in all the locations we all detect whether it is in western US or any where in the gold fields of Australia there is at least one spot that can stump all of us. This would be the spot that maybe we go and we know there has been good gold found there but for some reason we get skunked. This could be a spot that the geology is different than places we have success finding nuggets detecting. As we all know what's going on with the geology where gold is detectable is different everywhere. Knowing how the gold got to an area is very important for our success. Here is an example . In one area I detect Libby Creek the gold is on and in the bedrock as well as spread out thru all layers of gravel as though sprinkled from a salt shaker. I have this figured out. Another area you will not have much luck finding nuggets unless you are on the bedrock. Period. That is where the gold is in that area. The one exception to this in this area is hunting for specimens around lode mines. There is one place a friend of mine and myself have been going to detect for nuggets, each of us for a period of about 14 or 15 years and we both get skunked every time. I have held a 4 ounce nugget from this area found with a detector.  So with this knowledge and knowing that three guys found 300 nuggets in this area in one summer, we keep going back. This is the eternal optimism of all of us who detect for nuggets. This area that stumps my friend and I is all granite the rock outcroppings the loose rocks on and in the ground are granite. The bedrock is granite, even the regolith on the bedrock is all granitic in make up. So I thought maybe if we all share info on the geology in each of our nemesis localities,  perhaps someone out there has knowledge how to hunt these locals. I am not asking anyone to divulge the name and location of these areas, just the clues you have learned dealing with the geology in relation to the gold that led to success in similar sitiuations. Lets try putting our collective minds and knowledge together to help each of us. What is your nemesis spot. Maybe we all can help each other. Try to give all geological info that you know of too figure out the clues of where the gold might be hiding.

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This particular spot where my friend and I have been skunked for so long is very interesting. It encompasses two gulches separated by a mountain,the first gulch on the west is barren of gold on the east facing slope and is rich in manganese. The west facing slope is the slope that carries the gold. The country rock in this gulch is dominantly limestone. There have been large nuggets found here up to 9 ounces. Now on the other side of this mountain is the second gulch. This gulch is east of the first gulch. It has placer deposits all thru the gulch but the richest deposits were the alluvial gravel that made it out of the gulch, from the mouth of the gulch leading out to the gentle low rolling hills and out to the flats. The country rock in this gulch is dominated entirely by granite. It is part of the boulder batholith. An intrusive granitic deposit. This deposits are formed in the earth. That is why it is a intrusive igneous rock. I know the gold was carried in a volcanic ash derived gavels that was on top of the granite. Here is where it gets interesting like some unsolved murder mystery. Stay tuned for part 2 tomorrow.

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There is very little left of the volcanic ash derived gravel containing the placer gold. It has mainly moved down and out away from the mountain. There was these gravels and limestone on top of the granite. It has all eroded away. My buddy says the big gold that could not be transported by erosion stayed in the spots where every nugget was lying and instead just dropped straight down. There are huge granite outcroppings all over this gulch and all loose material is all desinagrated granite, even the placer deposit alluvium that made it out of the gulch, almost a mile away is all granite. So my question to all who read this. What do you think? Share your best opinion. I think I need to go to the top of the ridge because I believe this is the area where the contact zone is. My goal is to look for the area where I can see the limestone from the first gulch and the granite from the second gulch and detect between them.

 

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Yes. It states it in the mining journals on what gravel the gold is carried in and that it is various thicknesses. This ash has gravels mixed in with it. It was know as the tertiary lake beds. A large inland body of water. Much of western montana was covered by glacial lake missoula and glacial lake great falls. At at a period of time long before that much of montana was covered by a great inland sea much larger than these lakes. So that gives a very long time of erosion to clear out the regolith and the layer of limestone sitting on top of the granite. Perhaps since on this side of the mountain is absent of the limestone and the other side isn't then maybe this was a boundary of this tertiary lake. I don't know for sure. This area is known for large gold. Nuggets up to 9 ounces have been found here and one was found in the next gulch that was 27 pounds. No other gold was found in that gulch. Just the one nugget. Very perplexing isn't it.

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Ok, I have seen a lot of people mistake volcanic ash for several other possibilities such as sediment from an ancient hydrothermal vent, known to produce large   sporadic nuggets.

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Hi Goldseeker, Merry Merry Christmas and to you all!!

Had a few , being an Aussie holiday an all, “hic “

cool subject .

Look for country rock, sediment. look for valleys where on either side there be volcanoes of a certain age . Sediment is old. Sediment is crushed by Monolths , under sea mountains “ granit” +,that jostle about in the liquid state of the crust .volcanoes “ vent “the pressure between the mono’s and the sediment. The sediment is squeezed so tight it cracks, peculiar to a North South line. DunnolyVictoria AU.

In the fissures gold and its host silica squeezes.  “ I believe” ,through the pressure points. I hypothesis that Gold umongst other heavy elements make up the Earths core and is surrounded by silica, quartz and the lighter materials, that being minerals.

movement and hydrological action force fingers of heavy elements to the surface.

Grafity,Geology,  Sonar.   God Bless . God Speed.

 

 

 

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I don’t think that hard about it. I get into an area where gold has been found before, then I put my coil over anything that looks interesting. I found out long ago there is gold where I think it is not, and very often no gold where I think it should be. The only way to know for sure is to put the coil over it.

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  • 7 months later...
On 12/23/2017 at 10:01 AM, kiwijw said:

Geology & geography fascinates me & has from a young age....still does.

Ditto. Gold-specific geology and geophysical research having been my way of getting through the long winters for years and then come spring in late May to June getting out into the field on expeditions to find the indicators ... absolutely love it and is tough to pull back from that life-long interest. And on mountain climbs in the past, not for prospecting, but just to climb, having the know-how to spot and interpret rock formations specific to gold has really proved interesting. But ya what you, JW and Steve say is what has been realized just recently ... too much thinking makes it more complex than it has to be, and likely has led to walking right past some productive ground while out there pretending to be a geologist/ geophysicist.   

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