What ingredients make the ground nuggety?

[Stevoggo]

So...I am lurking and reading....and researching....

I understand about some geology

So i think gullies around old mine workings are good places to look.

But i often hear it said that gold around quartz reefs is too fine to produce good nuggets....
yet my understanding is the heavier larger gold would stray least far from its source?

Alluvial gold in banks of streams requiring sluices looks small and fine too...

So what kinda things help make gold a good size and shape for detecting?

I have searched the forum a bit before asking this.

many thanks in advance
Steve

 

[toecutta]

Good questions Steve... i will be following this to get some info myself

It may be worth you having a read of a post by loamer... a sticky under "Metal Detecting for Gold" called "What to look for on the goldfields (new to prospecting)"... if you havnt already of course ;-)

 

[dwt]

Wish I knew that!, stop me finding those .0000000grammers :lol:

 

[nuggetino]

Yep it's all here if you're willing to put in the time and read about it. Learning to read the ground maximizes your chances of finding gold but remember you are looking for a rare metal! That means you can cover a lot of ground with the right geology and find next to nothing. The best sign of a lot of gold is a little gold.
A little info about gold nuggets you may find helpful
http://www.gold-nuggets.org/rarity-natural.htm

 

[Stevoggo]

Wow! what a great reply nuggetino....thanks for that.

the first point was all i needed...my current understanding is that all nuggets eroded from rich quarz....or escaped via faultlines in a reef...

But that doesn't seem to be the case......which led to my initial post....

Also toecutta thanks i have read loamers posts....they are awesome....but I was after more info on geological conditions that form the nuggets...

TBH I'm not exactly sure what this means...
Now, the generally held belief is that nuggets formed very near to the surface as gold precipitated from solutions arising from chemical weathering of deep and diffused gold deposits.

But it sounds like what I was after!..

Cheers all
Steve

 

[WickedWaz]

My understanding is that big nuggets are formed deep down. Then brought to the surface through geological events, and water-table levels. You might find this interesting

http://www.csiro.au/Organisation-St...cience--Resource-Engineering/GoldNuggets.aspx

Waz

 

[Metamorphic]

Secondary gold in the form of 'secondary enriched' nuggets are the main interest of those with a metal detector.

I will try and explain.......In a basic sense, Primary gold is formed in reefs hundreds of millions of moons ago from dissolved gold in hot fluids that has crystallized upon either cooling, or a rapid drop in salinity, usually both.

Secondary gold forms at, or near the earths surface from 're-dissolved' gold of a nearby Primary source which has been exposed at, or above the water table in saline groundwater.
I mean this primary formed gold formed in the reef after erosion and exposure has now been dissolved again in near surface salty groundwater and carried down-slope under gravity (in solution) to be re-deposited near the surface along the valley floors and drainage points.

Secondary gold deposits are largely achieved when groundwater is diluted by rainwater.

As the salinity of the ground water decreases during rain events, the solubility of dissolved gold drops dramatically.
Tens of millions of rainfall events over the last few million years repeat this process, building up more and more layers of gold upon each other to eventually form larger nuggets.

Secondary gold is very young compared to its primary counterpart and is still forming today after rainfall events.

Primary Alluvial gold often can become secondary enriched by these events over time as well.

Cheers

 

[silver]

But all that was happening in antiquity as well,... thus all the gold found in old alluvium that's turned into sandstones and rocks and weathered back down and redistributed and worked on by rising oceans and shifting beaches and new volcanoes(in the past) and been metamorphosed and squeezed and tilted and turned upside down and,... then we come to the present day where,...as is always said,... Gold,... is where you find it.(ha).

 

[silver]

I like your answer much better than mine Metta !

Secondary gold in the form of 'secondary enriched' nuggets are the main interest of those with a metal detector.

I will try and explain.......In a basic sense, Primary gold is formed in reefs hundreds of millions of moons ago from dissolved gold in hot fluids that has crystallized upon either cooling, or a rapid drop in salinity, usually both.

Secondary gold forms at, or near the earths surface from 're-dissolved' gold of a nearby Primary source which has been exposed at, or above the water table in saline groundwater.
I mean this primary formed gold formed in the reef after erosion and exposure has now been dissolved again in near surface salty groundwater and carried down-slope under gravity (in solution) to be re-deposited near the surface along the valley floors and drainage points.

Secondary gold deposits are largely achieved when groundwater is diluted by rainwater.

As the salinity of the ground water decreases during rain events, the solubility of dissolved gold drops dramatically.
Tens of millions of rainfall events over the last few million years repeat this process, building up more and more layers of gold upon each other to eventually form larger nuggets.

Secondary gold is very young compared to its primary counterpart and is still forming today after rainfall events.

Primary Alluvial gold often can become secondary enriched by these events over time as well.

Cheers

 

[gcause]

Nah, gold is really just bug poop.

http://www.abc.net.au/science/k2/trek/4wd/Over44.htm

Apparently the elluvial gold patches that are found where no one can find the source i.e. reef, etc. is actually produced by bacteria over millions of years.

 

[Metamorphic]

Nah, gold is really just bug poop.

http://www.abc.net.au/science/k2/trek/4wd/Over44.htm

Apparently the elluvial gold patches that are found where no one can find the source i.e. reef, etc. is actually produced by bacteria over millions of years.

Yes i have researched somewhat into this relatively new geo theory on secondary gold formation.

As they state, the bacteria doesn't actually produce the gold itself, it just attracts the gold that is already re-dissolved in the saline groundwater, to consolidate towards larger nuggets upon depositing.
But yes, it seems very plausible that it plays an integral part in what we see as 'near surface' gold today.

http://crcleme.org.au/Pubs/Monographs/regolith98/14-hughes_et_al.pdf

Regards

 

[gcause]

John Parson over at the Prophet Gold Mine in Gympie has done the hard yards on this for years.

He has been involved in the study that proved the theory.

He supplied the raw materials for the study in the forms of mine tailings for the professors involved from the University of Queensland.

From those tailings they identified the specific bacteria involved.

Once identified they then grew gold.

Its not commercially viable yet to use this bacterial soup to grow gold in commercial quantities but one day they believe it will be.

 

[dwt]

Its not commercially viable yet to use this bacterial soup to grow gold in commercial quantities but one day they believe it will be.

CRIKEY!!, if the Alchemist of yesteryear found out about this theyd ***** their art smocks :lol:
if they did pull this off I wonder wether that would start affecting the gold price! :|

 

[Wintersnake]

Its not commercially viable yet to use this bacterial soup to grow gold in commercial quantities but one day they believe it will be.

CRIKEY!!, if the Alchemist of yesteryear found out about this theyd ***** their art smocks :lol:
if they did pull this off I wonder wether that would start affecting the gold price! :|

Probably just make the price go up coz` of manufacturing costs.

 

[Stevoggo]

Just wanted to say a thanks for those replies ...
Especially metamorphic's explanation of a secondary gold deposit.
I believe if have understood it !
Thanks to everyone tho.
Cheers
Steve