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Author Topic: Rusty sandrocks.  (Read 988 times)

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Offline marekn

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Rusty sandrocks.
« on: January 10, 2018, 04:22:25 PM »
Couple of years ago while panning NSR I stumbled on those interesting rusty rocks composed of rusty sand. For the volume of the specimen they seems to be a bit heavier than regular rocks.  I dipped few pans around but no visible gold were found.
Since the last interesting , strange looking rock I and tonofsteel we found past Fall I promised myself to take samples of the specimens . Close examinations might reveal some interesting information.
Do rocks like those are indicators of necessity to examine closely the area or just common occurrence ? Any lights on this?
Thanks.
MarekN
IMGP0492.JPG

Offline JOE S (INDY)

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Re: Rusty sandrocks.
« Reply #1 on: January 10, 2018, 05:42:51 PM »
Certainly I can't know a lot about that area in the NSR, but one small fact could come into play here.  Hematite and Magnetite are both Iron Oxides and, given a lot of time, moisture and oxygen they will eventually break down to a rusty reddish brown state of a simpler Iron Oxide. 

Where I mine that can often be the holy grail - with co-situated Gold and the heavier (SG 5.1+) black sands iron minerals residing in old, old catchments in or even just on bedrock.

For my area the original depositing of Hematite, Magnetite and Gold occurred before the glaciers "did their thing".  Over many thousands of years the breaking down of Iron ores left the Gold just sitting there - and that was L O N G  before the old timers worked the area.

Those red / brown deposits were usually covered by the glaciers and protected from the effects of weather, rivers and such.  Because of that they sit on bedrock and just wait to be found.

I happen to be in the process of trying to zero in on a "found and lost" very small occurrence of that exact condition and hope to zero in on it this coming season. 

So, thoroughly check out any Iron mineralization like that shown.

Joe
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Offline mcbain

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Re: Rusty sandrocks.
« Reply #2 on: January 10, 2018, 06:13:39 PM »
Hi.Marek.Just a thought.Is it possible it could be Lava rock.Definetly worth checking out.Luck Mcbain.
I started out with nothing Istill have most of it.

Offline GollyMrScience

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Re: Rusty sandrocks.
« Reply #3 on: January 10, 2018, 08:07:50 PM »
Along the North Sask and all over Alberta actually the iron rich sandstones, shales , mudtones and concretionary ironstones can be found.
Iron rich groundwater invading permeable rock and in the water when layers being laid down as rocks form.
You will find a lot of it in Alberta in varying forms.  As you go west of Edmonton you will encounter an area where the iron rich rocks were cooked into lava looking specimens by coal fires. An entire layer of it exposed out towards Drayton Valley.
To the south the iron rich bedrock layers are evident in and around Drumheller and in fact the iron has invaded and encased some fossils -Dino bone etc.
All part of the Edmonton Formation  and pictures of the Drumheller area will show the layer cake iron rich layers as dark bands in the hills.
Hard to give it a name as it can vary in purity and such -goethite - limonite -some hematite. Samples are often feeling heavier than expected.

What the heck - lets just keep mixin' stuff together till it blows up or smells REALLY bad!

Offline GollyMrScience

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Re: Rusty sandrocks.
« Reply #4 on: January 10, 2018, 08:27:17 PM »
When you smack them open depending on how it formed you might find a thin rusty crust of earthy goethite  or limonite on a nearly clean sandstone interior or you might encounter the concretionary form where successive layers of iron rich mud formed around lighter layers like an onion.  Invaded rock from groundwater tends to have iron in cracks and permeable sections while the type laid down as the rocks formed is more consistent throughout. Thin sheets - massive layers a couple feet thick of "bog iron" type mud stones - various combos of sedimentary iron, manganese, calcite etc- you name it. Coal rich and iron rich layers as well. The iron in groundwater in some places is astounding . Well water looking like chocolate syrup almost from iron and manganese so high that water treatment is a lost cause yet people are flushing their toilets with what looks like dark brown water and living with the stains as that all they can use it for. There is a reason we have a Redwater River and a town named Redwater. In a gravel pit near there I actually watched ironstone forming as fresh clay was exposed to a quiet pool of local groundwater and iron was coming out so fast you could see it forming on the clay ball surface over a couple of days. Amazing.
Have seen ancient and recent artifacts covered in layers of the stuff to the point that if a strange shaped ironstone is seen its worth checking for something inside. Dino bone and more modern mammoth, bison, etc. - First Nations stone tools and even remains of burnt wood in some.
The "blacker" varieties are typically higher in sedimentary manganese while the rustier more earthy look is more iron and lower manganese.
What the heck - lets just keep mixin' stuff together till it blows up or smells REALLY bad!

Offline GollyMrScience

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Re: Rusty sandrocks.
« Reply #5 on: January 10, 2018, 09:37:01 PM »
The original post says "Couple of years ago while panning NSR "
North Saskatchewan River at least thats the common abbreviation around this area of Alberta.
That stuff is such an obvious feature that I assumed it was the North Saskatchewan River they meant.
If in fact it is Northern Saskatchewan then all bets are off  <-laugh->
What the heck - lets just keep mixin' stuff together till it blows up or smells REALLY bad!

Offline marekn

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Re: Rusty sandrocks.
« Reply #6 on: January 10, 2018, 09:57:46 PM »
Hi GollyMrScience. Indeed this is the North Saskatchewan River but near Prince Albert , what makes even less attractive proposal. But to learn thing or two never bad idea.

Offline GollyMrScience

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Re: Rusty sandrocks.
« Reply #7 on: January 10, 2018, 10:05:27 PM »
Ah yes way more ironstone than gold out that far but same formation or its Saskatchewan equivalent  formation in the great sedimentary basin .
What the heck - lets just keep mixin' stuff together till it blows up or smells REALLY bad!

Offline ykplacer

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Re: Rusty sandrocks.
« Reply #8 on: January 11, 2018, 12:54:22 PM »
Couple of years ago while panning NSR I stumbled on those interesting rusty rocks composed of rusty sand. For the volume of the specimen they seems to be a bit heavier than regular rocks.  I dipped few pans around but no visible gold were found.
Since the last interesting , strange looking rock I and tonofsteel we found past Fall I promised myself to take samples of the specimens . Close examinations might reveal some interesting information.
Do rocks like those are indicators of necessity to examine closely the area or just common occurrence ? Any lights on this?
Thanks.
MarekN
IMGP0492.JPG

Looks to me it's red sandstone,I been and lived in places where buildings from way back , were  built with the red sandstone blocks and still standing today.Really nice old buildings standing the test of time,.As the stones age , they turn colors and eventually need to be cleaned with acids, which is a slow process and  very costly for the building owner!

With that said, i do remember reading a while ago, someone took some  red sandstone and put it under a microscope /crushed it , and low and behold there was"microscopic" gold in it..They was not expecting  that.

Offline ykplacer

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Re: Rusty sandrocks.
« Reply #9 on: January 11, 2018, 01:22:50 PM »
https://phys.org/news/2016-02-reveals-gold-millport.html

Quote
Normally gold deposits are found in 'veins' found deep in the Earth's crust which are produced by water flowing at high temperature.

However, analysis of common red sandstone rocks found at the beach at Millport on the island of Great Cumbrae in the Firth of Clyde has revealed tiny concentrations of gold that provide a tantalising clue that could eventually lead to the discovery of much larger deposits elsewhere.[/size]

Professor John Parnell from the University's School of Geosciences is the lead author of the study, which has been published in the Journal of the Geological Society.

He said: "In undertaking this research I was initially interested in analysing little structures found within common red sandstone rocks which we took from the beach at Millport, which to the naked eye appear as tiny black spots.

"By analysing the structures using a high-powered microscope, we discovered that they contain concentrations of gold, which is unusual because gold normally tends to be concentrated by hot waters rising up through cracks in the Earth.

"In this this case the gold has been formed and concentrated in a completely different environment, which raises the possibility of similar structures appearing within red sandstone elsewhere but on much bigger scale."

The research adds to a growing awareness that concentrations of gold are present in red sandstone or other common sedimentary rock, otherwise known as 'red beds'.


Read more at: https://phys.org/news/2016-02-reveals-gold-millport.html#jCp