Rich Hill Geology

[mbcougartl]

I have heard from several people that think that there is/was a steam vent or gieser at the top of Rich Hill. Does anyone else have any information about this?

Well! If it does, I can bring the volcanologist for measuring and sulfur testing. I aware of Rich Hills to be extinct volcano. I went there at many times. It cannot be active until any further notice. It depends on magma uprising and do whenever it would take. You can see it yourself with your prospectors to know more detail about the Rich Hills. Ask Chris Gholson or any geologists. Thanks!

[Uncle Ron]

There is a legend about a feature of Rich Hill called the "Cough Oir" or "Golden Cup." It supposedly relates to a golden deposit deep in the hill that was blown out by volcanic sources, scattering nuggets all over...Personally I don't think that makes any sense and I adhere to the explanation given in the book Chris G. and his associates presented in their book. Yep, that's what I think...Cheers, Unc

[Reno Chris]

Rich Hill is made mostly of granite. Granite is an igneous rock, which means it was once molten. Not all molten magma however, makes it to the surface to be erupted out a volcano. Granite is a rock that forms when the magma has a chance to cool slowly while deep within the earth. So no, Rich Hill itself is not a volcano. There are volcanic rocks like basalt in the area around Rich Hill, especially covering the higher hills to the north. Basalt comes out of volcanoes and related vents so there are some volcanoes or vents around Rich Hill in the general area.

The idea of volcanoes blowing out molten gold which forms nuggets is an old one that has no science whatsoever to support it. It comes from the appearance of gold nuggets that are blob-like and smooth, because they kind of look like they were once molten and cooled and solidified into those smooth, blob shapes. There are gold districts in California with names like Volcano and Volcanoville because the old time 49ers believed that some giant volcano shot out molten gold and scattered that gold all over the California gold country. There are no real volcanoes any where near Volcano or Volcanoville in California. All real nuggets have a crystalline pattern on the inside, which is revealed if you cut and etch them. Although the pattern is much different in appearance, the concept is similar to what you would see on the inside of iron meteorites. These crystals show that nuggets form by slow growth, not quick solidification after being shot into the air by a volcano.

Chris

[nuggethunting]

Hello Guys,

I know about this "Cough Oir" or "Golden Cup" very well and it does exist on top of Rich Hill. I was a carekeeper for many years under the old owners, Jack and Laura Culp. Laura used to talk about the "mud pipe or vent" often. Her Grandfather actually tried to tunnel into the "vent" to find the source of a lot of the gold on top of the mountain. I've been to the "vent" many times and even in the tunnel her Grandfather dug and worked. One of the patented claims on top of the mountain is called "Cough Oir."

The "pipe or vent" is actually the remains of an old Hydrothermal vent. There are many signs of the vent, one sign is the Kaolinite clays that are seldom found around alteration zones. This was just one source and actually not the more productive one on the hill. The gold from this source is much more "buttery" color compared to many of the other veins around Rich Hill.

I actually have a Geology background and found less gold when I spent years studying the books. More book work and less field work caused me to believe the books too much and put "blinders" on and only see one dimentional, if this makes any sense. I probably have 200-300 books on geology, ore deposits, mineralization, rocks and minerals and just about every freaking US bulletin, open file report, old maps and anything else you can get your hands onto. A good friend used to own a used and rare book store, so I pretty much got everything that he came across in the US.

Take care,

Rob Allison

[Dakota Slim]

Rob, what color is the Kaolinite clay you are referring to?

[nuggethunting]

Hey Dakota Slim,

The Kaolinite clay in this spot is a dull White and very Earthy looking. The clay can be various colors depending on the weathering of other minerals present. I've seen this clay from Yellowish to Reddish in color in different locations thoughout the Southwest.

Take care,

Rob Allison

[Dakota Slim]

It would be interesting to see a very detailed geographical map of Rich Hill and the immediate surrounding area.

Chris Ralph you said, "Mt St. Helens had a bunch of rhyolitic / granitic type magama in it, and BOOM - those gasses in the magma were what caused that mountain to blow up into a pretty spectacular explosion. Cauldera volcanos also have high silica tyes of magma that are of the rhyolitic / granitic types and they cause explosions that make Mt St. Helens look like a toy pop gun by comparison." I wouldn't rule that type of event out in the overal Rich Hill picture.

There are the obvious huge granite boulders as well as what Montana says appears to be rhyolite and silica along with rich red clay and green decomposing bedrock, hematite, magnetite and quartz. There is also what Elly calls "Potato Soil", which is grey, and the 2 ounce nugget I found with my Gold Bug 2 was in a band of potato soil that was sandwiched between the red clay and the ryolite.

Rob, you and a few others know exactly where that is. The reason I stumbled down that alley was because the GB2 couldn't handle the hot red clay. That nugget, and 2 other nice ones I found withing spitting distance, were all the rich buttery yellow gold.

Of course there is no telling how these nuggets got to where they were but finding them has sure made me curious and hungry for more information.

Here's a blast from the past to fire up the fever...

[Reno Chris]

Slim - the huge difference between granite and rhyolite is exactly as you say rhyolite comes to the surface and has a hard time flowing out of a volcano, so it has a tendency to create explosions. The mineral crystals that make up Ryholite are microscopic because they form really fast as the magma cools. There is loads of Ryholite and Rhyolite tuff in parts of Nevada. Granite cools slowly, deep down in the earth and forms crystals that are easy to see, commonly 1/8 to 1/2 inch in size. granite comes up to the surface by uplift and erosion - it does not cause any explosions. The Rich Hill Granite looks like granite.

The lighter part of the salt and pepper rock is granite from the Sierra Nevada. You can see the crystals easily.

The gray rock is rhyolite with microscopic crystals.

They both have the same chemical make up, but are very different in appearance.

Of course you are welcome to think whatever you like.

Not sure what Rob is saying about Kaolin - it forms around alteration zones, but also is a product of just normal weathering of rocks that contain feldspar (like granite). Its the most common type of clay. Kaolin is white of itself, but is often colored by iron or other oxides with it and can appear all sorts of tan, gray, brown and brick red sorts of colors, depending on the impurities that are mixed with it.

Chris

[nuggethunting]

Hello Reno Chris,

I was just stating where this "mud pipe," or Hydrothermal vent is located, there is a lot of Kaolinite clay at the surface. I believe this location is one of the sources of the gold on top of the Mountain. This system is not related to the Johnson Mine ore body from what I've seen.

Take care,

Rob Allison

[Dutchman]

I found an interesting article about geothermal deposition of minerals:

Geothermal production wells with high fluid fluxes are the main sites of precious-metal mineralization. The deep chloride water (with or without minor amounts of vapor) enters the well at depths >500 m and undergoes a pressure drop that causes boiling. As a result, precious metals precipitate and accumulate as scales on back-pressure plates or as detritus in surface weir boxes; these deposits contain <10 to >1,000 mg/kg Au, <100 to >10,000 mg/kg Ag and ~10 to ~1,000 mg/kg As and Sb, each. Within production wells, platy calcite deposits as a scale at the site of first boiling near the fluid feed point, while crustiform-colloform-banded amorphous silica deposits in surface pipe work. By contrast, the hydrothermally altered host rocks contain low concentrations of gold, ranging from <0.01 to 1.0 mg/kg Au (68 analyses), and these correlate positively with arsenic (<100 to ~5,000 mg/kg) and antimony (<10 to ~500 mg/kg).

Reaction path modeling using SOLVEQ and CHILLER shows that calcite, K feldspar, gold, and amorphous silica deposit in sequence from a chloride water that cools along an adiabatic boiling path (300° to 100°C), analogous to fluid flow in a production well. By contrast, calcite, quartz, K mica, and pyrite deposit from a chloride water that cools due to mixing with CO2-rich steam-heated waters; dilution prevents precipitation of precious metals. Thus field observations and reaction path modeling demonstrate that boiling is the main process influencing the deposition of precious metals.

The results of this study show how peripheral hydrolytic alteration by CO2-rich steam-heated waters relate to propylitic and potassic alteration by chloride waters in the epithermal environment of a hydrothermal system. Both the distribution of alteration mineral assemblages associated with the different water types and the broad-scale distribution of temperature-sensitive smectite and illite reflect the location of the upflow zone. On a local scale, the occurrence of platy calcite, crustiform-colloform silica, and K feldspar in veins indicates the existence of boiling conditions conducive to precious-metal deposition.

Here is a link to the full article: http://econgeol.geoscienceworld.org/cgi/co...stract/95/5/971

[Bandana Don]

My knowledge of geology is admittedly very limited so I'd appreciate knowing what the white soft clay like substance is in the Beehive Mine. Ben Jaffe showed me a small adit in the white clay (?) where there are thin veins of beaytiful crystalized gold. I have always thought the clay material was Kaolinite but not sure.

Haven't seen or spoken to Ben in several years so have no idea if he still owns the Beehive Mine.

Don

[nuggethunting]

Hey Don,

Not sure what the White might be over at the Beehive, haven't been around that place in a long time. However, it would surprise me if it was Kaolinite.

Ben is still out there, actually mining the Twin Tunnel area, East of the Beehive Mine. He also now owns the Octave Mine and surrounding claims. You can visit his Beehive Mine website at - http://beehivemine.com/home.php

Take care,

Rob Allison

[whats4supper]

perhaps the white mineral is a variation of talc or talcite. a lot of prospectors skipped over values at goldfield, because they were taught that gold isn't anywhere near or in talc deposits. of course, much of the placer gold and vein gold in and around goldfield (nv) had talc associations. talc or soapstone is actually a metamorphic rock, associated usually with schistose, dolomite (limestones) and silicates (quartz)