Think gold veins take a long time to form? Think again!

[UncleMatt]

Hey All, I saw this article and thought everyone might find it interesting. It never occurred to me before that fissures with mineral laden water under very high pressure that experience a rapid drop in pressure might form mineral veins in a very short period of time.

Earthquakes make gold veins in an instant | Geology IN

 

Amazon Forum Fav 👍

Agony and Death on a Gold Rush Steamer: The Disastrous Sinking of the Side-Wheeler Yankee Blade - Grab it through Amazon!

[No gold in NY]

Very interesting concept. Thanks

 

[Ragnor]

Yeah, that's pretty cool ain't it? Ive known this for a couple of years now. It really changes the paradigm when considering geology and crystallography on all levels.

 

[UncleMatt]

This makes a lot of sense if you think about it. If you have salt water under high pressure and way above boiling temperature and then suddenly release the pressure, the water will flash into steam and leave behind the salt on the container walls. Its the same for any mineral contained in a water solution, even gold.

 

[Ragnor]

My brother and i have been discussing this in relation to the hydroplate theory. Which involves a massive cracking of the earths crust allowing deep reservoirs of water to come rapidly up out of the crust under great pressure. Now we know that deep hole drilling often hits what they term as salt water at depth. Now instead of salt water what if we call it a sodium silicate solution? What's gonna happen if you pop the cap on that? It's going to rapidly cool and crystalize sort of welding back closed the crack.
Now if we kind of look at the earth as a living organism this sodium silicate solution functions something like lymph in the human body. Making the solidified silicates something like the same material that forms scabs when our outer crust gets broken. Allot of it just depends on how far down the rabbit hole you wanna go to make sense of it all.

 

[UncleMatt]

This makes me wonder if you could extract gold or other pay metals from subterranean water simply by bringing it to the surface and removing its pressure.

 

[Goodyguy]

This makes me wonder if you could extract gold or other pay metals from subterranean water simply by bringing it to the surface and removing its pressure.

Could you use the technique to remove gold from seawater?

 

[bobw53]

Back in the college days, my GF's friend was a geology major..

Geology? Who wants to look at rocks all day?? I thought it was the only job/major that
could make accounting look exciting.


NOW I get it.

 

[Cassews]

Interesting article for sure .. Thanks for sharing !

 

[Ragnor]

This makes me wonder if you could extract gold or other pay metals from subterranean water simply by bringing it to the surface and removing its pressure.

Some larger companies have been testing it out with limited success.

 

[UncleMatt]

Could you use the technique to remove gold from seawater?

Not unless the seawater had first gone deep underground where it was subjected to high levels of heat and pressure. And I'm not certain, but the amounts of gold dissolved in seawater would be fairly low.

 

[UncleMatt]

What I would like to understand is the circumstances that create a gold rich water solution. I understand how the gold is dissolved by high temperature water, what I don't quite grasp is why some subterranean water has gold dissolved in it and some does not. Is it just random chance that water is exposed to gold deep in the earth, or what.

 

[TerryC]

Could you use the technique to remove gold from seawater?

A very interesting view on a very old subject, Goodguy. The extraction techniques today say the 1 oz of gold found in each cubic meter(ton?) of seawater is too expensive. Maybe they're on to something! TTC

 

[Clay Diggins]

There are a lot of different circumstances where a saturated solution of gold can be separated from it's salts and form relatively pure elemental gold deposits. Pressure drop is part of the equation and has been known for a long time (centuries). The source of the pressure drop is not just earth movement nor is it always quick. There is good evidence that lightning strikes can create a similar situation to earth movements.

Notice that I started by proposing a situation where there was a saturated gold salt solution. That points to the biggest factor that must be present to deposit gold. There must be a saturated salt solution that contains a considerable percentage of gold. Those gold/salt solutions aren't just hanging around, they had to be created first. That most often is accomplished with great heat and pressure in the presence of iron, chlorine, silicon and of course considerable gold. Other combinations metals/halogens can work similar magic but the iron chlorine, silicon gold is the most common. In other words free gold deposition requires just the right chemistry. If the chemistry isn't right there will be no free gold deposited no matter what the pressure, electrical potential or heat change.

In real life this is very complex stuff. No deposit ever just had those three metals and one halogen. There is always a lot more complexity to the saturated solutions found in mineralized areas. If it was as simple as finding a few metals and a halogen gold deposits would be easy peasy to discover, mine and separate. This article points out just one of the mechanical factors needed to create a gold deposit. This isn't new knowledge and it isn't the whole picture but it is an important piece of some puzzles. Other puzzles not so much. It is clear that not all gold is deposited quickly nor is it always deposited due to a rapid pressure drop. If it was that simple all gold found in veins would have perfect crystal structure. Most gold found in veins has no crystal structure or it has false crystal structure due to pseudomorphism.

The myth of seawater containing significant quantities of gold have led some down very convoluted paths to understanding gold deposition. Seawater contains approximately 1 thirteen millionths of a gram of gold per cubic meter. In other words it would take 13 million cubic meters of seawater to produce 1 gram of gold - if you could find a way to actually separate out those atoms of gold from 3.4 billion gallons of seawater you would have 1 gram of gold worth $47. Hardly a paying proposition.

Gold is rare stuff by any calculation. It's even rarer in concentrated enough form to produce a paying mine. If it weren't we would probably be prospecting for emeralds or lead. Soak up all the information you can get on how the golden element is deposited and try to envision how that works in real life. Every bit of this information can help you find a good gold deposit but no single piece of this information will get you there. This prospecting stuff requires a lot of knowledge and the more real facts you can put together the greater your chances of finding gold. It's still out there - go get u sum!

Heavy Pans

 

[TerryC]

Clay, I retract my statement on the amount of gold in seawater. You are right, but you leave me confused on another point. It is my belief that cyrstals are formed from slow cooling. Slower cooling... bigger crystals. Is that what you are saying? Further, I re-read the article and no where does it state where this pressure release takes place. They can only take place deep within the earth, where the heat and pressure takes place. the quartz veins(with gold) only become visible by plate tectonics(mountain building) and erosion(exposing the vein). And I appreciate your posts. Tnx. TTC

 

[Clay Diggins]

It is my belief that cyrstals are formed from slow cooling. Slower cooling... bigger crystals. Is that what you are saying? Further, I re-read the article and no where does it state where this pressure release takes place. They can only take place deep within the earth, where the heat and pressure takes place. the quartz veins(with gold) only become visible by plate tectonics(mountain building) and erosion(exposing the vein). And I appreciate your posts. Tnx. TTC

You make a good point about crystal size. It's true that slower cooling usually allows larger crystal formation. That's also dependent on the chemistry present but the cooling rate is a major factor in crystal size. I didn't address crystal size in my post but it's also known that pressure release is associated with higher solution temperatures. The heat factor goes up as the pressure goes down all else being equal. All that energy has to go somewhere and it is usually expressed as elevated temperatures as well as deposition from solution.

The article is about rapid depressurization causing gold deposition from solution along fault surfaces. There is a heat factor expressed in their observations but they don't address the attendant heat rise that is part of that process.

What their calculations revealed was stunning: a rapid depressurization that sees the normal high-pressure conditions deep within Earth drop to pressures close to those we experience at the surface.

When mineral-laden water at around 390 °C is subjected to that kind of pressure drop, Weatherley says, the liquid rapidly vaporizes and the minerals in the now-supersaturated water crystallize almost instantly – a process that engineers call flash vaporization or flash deposition. The effect, he says, “is sufficiently large that quartz and any of its associated minerals and metals will fall out of solution”.

I doubt that you will ever see temperatures approaching 390 degrees Centigrade (734 degrees Fahrenheit) near the earth's surface so obviously these type of gold deposits would have to be exposed through weathering or be dug at depth. The depth thing is already being done with mines exceeding 13,000 feet in depth. It's hot down there but nowhere near 734 degrees. On the other hand many orogenic gold enrichment zones take place at or within a few hundred feet of the surface. The water table being the controlling enrichment factor. More than 75% of the gold ever mined comes from orogenic deposits often enriched at or near the surface.

The point being that these flash depressurizations might be significant in some types of gold deposits. The authors don't seem to have addressed what happens within the next few seconds/hours when the solution temperatures and pressures once again stabilize to the local norm. They recognize that things do return to steady state but they don't consider that the metals and salts might just go right back into solution with no effective gold deposition left in place. It would stand to reason that at those huge pressures and temperatures the minerals would just go back into solution like they were before the pressure was released.

When you look at the body of knowledge about the concentration of gold at depth several things become evident - we think, we surmise, we assume and we theorize. The "science" of geology has a long way to go before it can describe anything but some of the possible causes of gold deposition. We know a lot about the chemistry but there is little hard knowledge of the physical processes causing concentrations of gold.

The recent revelations about the probable causes of Australia's gold reefs and the theories going around about the Carlin Trend gold mineralization point to one big fact - we don't know all the facts and we can often only guess at the actual processes that form concentrations of gold at any given spot on earth. To me that's exciting and fascinating. A "science" that's just beginning to figure out some of the parts of the whole leaves open a huge playing field for the inquisitive mind.

It's still out there! go get u sum!

Heavy Pans

 

[TerryC]

Beautiful dissertation Clay, tnx. TTC

 

[UncleMatt]

I am sure some vein deposits of gold were formed over long periods of time, and others were formed in short periods of time. The hardest part still is locating where gold rich water far below the surface once flowed, or is flowing today. When pressure is released on high temperature water, the energy goes into vaporizing the water into steam. Usually when pressure is reduced, temperatures go down, simply because reducing pressure usually involves increasing the volume of the area where the liquid is being contained within. Which is what drives this instantaneous gold deposit formation theory. When earthquakes cause veins where gold rich water is flowing to enlarge in size OR to open them up to atmospheric pressure at the surface(which is far lower), gold will precipitate out of the water as the water flashes into steam. And such precipitations might close off the vein to more water coming in, or the fact that the vein is now no longer pressurized prevents any water coming back into it from achieving the temperature and pressure necessary to re-dissolve the gold back into solution.

 

[Clay Diggins]

I am sure some vein deposits of gold were formed over long periods of time, and others were formed in short periods of time. The hardest part still is locating where gold rich water far below the surface once flowed, or is flowing today. When pressure is released on high temperature water, the energy goes into vaporizing the water into steam. Usually when pressure is reduced, temperatures go down, simply because reducing pressure usually involves increasing the volume of the area where the liquid is being contained within. Which is what drives this instantaneous gold deposit formation theory. When earthquakes cause veins where gold rich water is flowing to enlarge in size OR to open them up to atmospheric pressure at the surface(which is far lower), gold will precipitate out of the water as the water flashes into steam. And such precipitations might close off the vein to more water coming in, or the fact that the vein is now no longer pressurized prevents any water coming back into it from achieving the temperature and pressure necessary to re-dissolve the gold back into solution.

Good points UncleMatt. The Gay-Lussac law of gas volume/temperature does play a part and assuming the gas volume doesn't change that law would lead to loss of heat energy as the pressure is reduced. I presume that is where you reached the assumption there is a net heat loss?

Of course there is a lot more in play than simple absolute gas volume/temperature. The latent heat of crystallization plays a large part in that heat equation when you are talking about saturated solutions crystallizing.

When you go from a high energy state of matter (gas, melt or liquid) to the low energy state of solid matter there is a release of heat energy. This is known as the latent heat of crystallization. You have to get rid of the latent heat of crystallization, in order to form crystals in the solid. Then you get an undercooling phenomena and super saturation before crystals can form, because the atoms work to get rid of the latent heat of crystallization before crystals can form. This heat has to be released and taken up by something else before crystallization can happen. So you have the cooling inherent in converting a liquid state to a gas and the resultant heating of a liquid state metal crystallizing as a solid.

When crystallization occurs there is an exothermic reaction that releases heat back into the solution/vapor. This is an important point in understanding crystallization/deposition of metals and salts at great pressures and heat. Often the deposition fails because of the excess heat pushing the same crystallizing metals right back into solution - resulting in an endothermic reaction (heat loss) to once again equalize the solute/pressure.

This is complex stuff but it's important to understanding how these ore bodies form. Not surprisingly that heat/pressure endothermic/exothermic balance is often tipped one way or another by the chemistry interactions within the melts, solutions and solids.

Here is an interesting take on how these interactions create the very same cracking and deposition that may take place in earthquakes and result in metallic ore bodies.
Here is a very interesting paper on how different magma chemistry depressurizations result in different temperature gradients. Notice how the chemistry of one example results in cooling as the magma depressurizes, expands and crystallizes and a different chemistry results in accelerating heating as the magma depressurizes, expands and crystallizes. Chemistry being the defining factor not heat or pressure.

I simplified when I explained the crystallization deposition as creating an increase of heat in the solution and you simplified when you explained that a reduction in vapor pressure resulted in a decrease in heat. The truth is mother nature could care less about simple answers and often produces unique and valuable lessons in just how it really works out. I for one am fascinated by the interplay of natural laws like the Gay-Lussac equation and the latent heat of crystallization. I like the variety and complexity of natural life and as long as I try to explain it in simple terms old ma nature will instruct me with the reality of a complex world. That's a good thing in my book.

Thanks for the thoughtful reply Matt.

Heavy Pans

 

[UncleMatt]

The heat performs work when it vaporizes the water into steam. The heat transforms the state of the water from a low order of energy to higher order of energy, from a dense liquid to a super heated gas. The volume of the system DOES change when the fissures with high pressure are made larger by the earthquake, or open the fissure to the surface. And any energy contained in the high pressure system, including the potential energy of mineral crystallization, is expended on vaporizing the water, ejecting the water/steam from the fissure, and also heating the country rock through which the fissure passes. Once the heat is lost in that way, it is no longer available to once again dissolve the gold back into a solution.