False bedrock

[Reeks]

Im curious how this is formed, i think i have come across it in my digging.
It looks like crushed kitty litter and is very hard to pick through. My shovel slides straight over the top and i have only penetrated it around 100mm to do a test pan on the gravel with the result being no colour.

There is a nice wash layer sitting on top of the false bedrock which has very coarse gold in it.

Here is a pic of the stuff, notice the red staining and the slight uphill gradient the FB is taking. The red stains are perpendicular to the river flow. Estwing pick for scale.

Look forward to what you guys think.
Reeko

 

[Teemore]

Not qualified to comment on your query but have a supplementary question that probably fits your post .....
You mention doing a test pan .... From those that know .... Who many 'test' pans would be appropriate?
I've bought home buckets of cons and many would not show colour but the overall lot does, if you give it away with the first pan likely to never find anything.
Sorry to barge in on your post,
Tom

 

[Reeks]

Anyone?

 

[headbut]

I would ask SWright , send him a PM

 

[TenOunce Tone]

Looks like granit.. got that pinkish tinge to it..

 

[axeman]

I'm no expert but it looks like sandstone, granite type of rock.
Mick

 

[Reeks]

Correct, the area is granite. I will shoot swright a pm.
Does anyone know if bedrock can decompose? Or is what im picking through sedimentary?

 

[axeman]

It would decompose. When they discovered gold in one field up here they found it wasn't coming out of a quartz reef but out of the granite.
Mick

 

[Palmer Digger]

Gedday there Reeks .. Nice bit of 'classic' gold bearing ground you have there and this is the part of the prospecting cycle where the fun begins! .. By fun, I mean that you're on the learning curve, and as you've said you are finding course gold in the wash layer .. Lucky you all round .. Important thing to note here, is that the courser the gold, the less distance it has travelled from it's original source to to deposit zone where it now sits.

Hard to tell from the pic to tell from the pic but it would seem that the 'false bedrock', as you describe it, is a much older concretion layer on which later material now sits. Judging from the exposed tree roots in shot, this looks pretty deep with lots of rounded water-worn rocks dispersed through it .. (Please don't leave your beautiful, expensive Estwing Geo Pick lying in the wet slop like that or it will bugger up the compressed leather handgrip quicktme , ay!) ..

From experience, I'd suggest that the interface zone, the lower dozen or so centimetres between the two, is will be where your riches lay, so to speak .. But don't discount the concretion layer .. This material can and usually does hold a few secrets of its own!

Have you sampled further up and down the system for colour?
Are you detecting this area as well?
Assuming that you're working a creek, or gully here, does go dry later in the season?

Let me know, as I said at the top, I reckon you're on to some classic country here, and not too dissimilar to some of the ground I work on the leases.

Good find, and Good Luck to you.

 

[rc62burke]

Very Hard to work it out from the pic!! Just a ?? why do you think it is "False Bedrock" to me it looks like this is the Bottom, yes it can decompose.
cheers
Lee

 

[Twapster]

Grab a seat, 4 foot crow bar and start smashing down.

 

[Reeks]

Gedday there Reeks .. Nice bit of 'classic' gold bearing ground you have there and this is the part of the prospecting cycle where the fun begins! .. By fun, I mean that you're on the learning curve, and as you've said you are finding course gold in the wash layer .. Lucky you all round .. Important thing to note here, is that the courser the gold, the less distance it has travelled from it's original source to to deposit zone where it now sits.

Hard to tell from the pic to tell from the pic but it would seem that the 'false bedrock', as you describe it, is a much older concretion layer on which later material now sits. Judging from the exposed tree roots in shot, this looks pretty deep with lots of rounded water-worn rocks dispersed through it .. (Please don't leave your beautiful, expensive Estwing Geo Pick lying in the wet slop like that or it will bugger up the compressed leather handgrip quicktme , ay!) ..

From experience, I'd suggest that the interface zone, the lower dozen or so centimetres between the two, is will be where your riches lay, so to speak .. But don't discount the concretion layer .. This material can and usually does hold a few secrets of its own!

Have you sampled further up and down the system for colour?
Are you detecting this area as well?
Assuming that you're working a creek, or gully here, does go dry later in the season?

Let me know, as I said at the top, I reckon you're on to some classic country here, and not too dissimilar to some of the ground I work on the leases.

Good find, and Good Luck to you.

Hi Palmer Digger,
Thanks for your input! I was suspect as to this being a decomposing bedrock. A concretion sounds alot more plausible.
I have found no flat or weathered gold at this location, for the small amount of wash i have processed i have come away with a 1.39grm flat nugget, a 0.05 picker and around 30 nice specs.
See my "lucky walbanker" thread for pics.

I have done some samples elsewhere for no colours
I have not taken a detector there as i don't have one. Looking at borrowing a gp3500 next time i go there.

Is there any way of telling how deep the concretion is? Maybe i will man up and try hitting real bedrock, but boy its hard to pick through.
The gold is almost bubbly (see pics in other thread) telling me I'm close to its source.
Your right, it's a big learning curve - mistakes will only make my back stronger.
Any explanation of the red staining and how it runs perpendicular to the river? Also how it rises up on an angle?

Thanks again.
Reeko

 

[Reeks]

Grab a seat, 4 foot crow bar and start smashing down.

Sounds good twapster, i recently bought a 6ft spud bar that weighs a ton.
Will give it a thump next time I'm out there

 

[Twapster]

6ft is too long, u need to cut 2 or 3 feet off to really crack into a hole without killing yourself. You will be surprised how quickly you can get down and dig to China if you have to. Its more just thinking about it that will make you tired. Slow and steady and you may be 5 feet down in no time. Just visualise there's a 50kg nugget a few inches further.

 

[Wally69]

Good looking ground Reeks.

It looks like sedimentary rock formed from decomposed granite to me, the constant grain size would not be unusual in the inside of a bend of a slow moving granite country creek. I would theorise that a change in the stream bed is what has deposited your paydirt and I would work that interface layer well as it may have not been cemented when the creek changed course and gold may have penetrated the layer, a careful test by layered sampling should give you an indication if it is worth breaking out the first few inches or not.

The lack of granite plates in the layer prejudices my thoughts that it is sedimentary. I would dig a hole and see if there is a second pay layer myself.

If you encounter granite plates down a bit deeper I would call it a decomposed bedrock layer and be satisfied that you have a good couple of months work ahead of you processing the paydirt, finding the honey holes and then securing your future prosperity by locating the source.

Good luck, keep us posted. :lol:

 

[Reeks]

Good looking ground Reeks.

It looks like sedimentary rock formed from decomposed granite to me, the constant grain size would not be unusual in the inside of a bend of a slow moving granite country creek. I would theorise that a change in the stream bed is what has deposited your paydirt and I would work that interface layer well as it may have not been cemented when the creek changed course and gold may have penetrated the layer, a careful test by layered sampling should give you an indication if it is worth breaking out the first few inches or not.

The lack of granite plates in the layer prejudices my thoughts that it is sedimentary. I would dig a hole and see if there is a second pay layer myself.

If you encounter granite plates down a bit deeper I would call it a decomposed bedrock layer and be satisfied that you have a good couple of months work ahead of you processing the paydirt, finding the honey holes and then securing your future prosperity by locating the source.

Good luck, keep us posted. :lol:

Thanks wally!
I will try to get through the concreted layer and test pan on the way down.
I am being made redundant in two weeks so i will put a good effort in while i have some time off.
Thanks
Reeko

 

[rc62burke]

Good looking ground Reeks.

It looks like sedimentary rock formed from decomposed granite to me, the constant grain size would not be unusual in the inside of a bend of a slow moving granite country creek. I would theorise that a change in the stream bed is what has deposited your paydirt and I would work that interface layer well as it may have not been cemented when the creek changed course and gold may have penetrated the layer, a careful test by layered sampling should give you an indication if it is worth breaking out the first few inches or not.

The lack of granite plates in the layer prejudices my thoughts that it is sedimentary. I would dig a hole and see if there is a second pay layer myself.

If you encounter granite plates down a bit deeper I would call it a decomposed bedrock layer and be satisfied that you have a good couple of months work ahead of you processing the paydirt, finding the honey holes and then securing your future prosperity by locating the source.

Good luck, keep us posted. :lol:

First Point- sedimentary rock is on an earlier time scale than Granite.
Second point- Granite plates??? Granite forms boulders & blocks it does not form Plates, Schist type rock forms "Plates"

Reeks
What type of country rock is the norm in your area?? this will tell you what you are looking at, also get hold of a geological map of your area, with the gold you are finding, To me you really want to understand the reasons why it is there to help you to find out where else it may be as it could be your indicator.
Good luck, whenever I have a puzzle like this I always fall back to "Research"
Lee

 

[Wally69]

Thanks for your input Lee, happy to be corrected but let me put some more context around my offering to clarify where my mindset falls on this one.

Sedimentary is used in the context of weathered granite rock, water deposited and subsequently bonded together. As this material appears to be bonded but able to be excavated by hand Tools I am happy with my terminology but would consider the bonding to be very weak and subsequently geologically young.

My understanding of granite is constant with yours in that granite is massive when formed and under weathering tends to block fracture and over time leave residual boulders exposed as the edges round. My experience with granite county is that it generally weathers like an onion skin, with plate-like sections breaking away, albeit initially shaped to match its host rock, either slightly curved or flat. My experience is that weathered granite is generally friable and a mixture of friable and plate-like material is commonly encountered when excavating into naturally weathered granite ground.

I am also a strong believer that terminology is, and will continue to be, a constant cause of confusion and the reader is entitled to as much right to interpretation as the writer.

Am I technically correct? I could be completely off the mark as I do not have a PHD in Geology :8 , but happy to offer my experience and opinion.

 

[Palmer Digger]

Well Reeks Old Mate, what more can I add to the erudite opinions above, .. I'm just a gold miner .. Good luck old boy.

 

[Reeks]

Good looking ground Reeks.

It looks like sedimentary rock formed from decomposed granite to me, the constant grain size would not be unusual in the inside of a bend of a slow moving granite country creek. I would theorise that a change in the stream bed is what has deposited your paydirt and I would work that interface layer well as it may have not been cemented when the creek changed course and gold may have penetrated the layer, a careful test by layered sampling should give you an indication if it is worth breaking out the first few inches or not.

The lack of granite plates in the layer prejudices my thoughts that it is sedimentary. I would dig a hole and see if there is a second pay layer myself.

If you encounter granite plates down a bit deeper I would call it a decomposed bedrock layer and be satisfied that you have a good couple of months work ahead of you processing the paydirt, finding the honey holes and then securing your future prosperity by locating the source.

Good luck, keep us posted. :lol:

First Point- sedimentary rock is on an earlier time scale than Granite.
Second point- Granite plates??? Granite forms boulders & blocks it does not form Plates, Schist type rock forms "Plates"

Reeks
What type of country rock is the norm in your area?? this will tell you what you are looking at, also get hold of a geological map of your area, with the gold you are finding, To me you really want to understand the reasons why it is there to help you to find out where else it may be as it could be your indicator.
Good luck, whenever I have a puzzle like this I always fall back to "Research"
Lee

Hi lee, the rock is your typical grey granite.
I am taking onboard what everyone is saying.
The wash layer contained alot smoother rock as well as some very rough granite boulders (basketball size)

I will follow the wash layer and try to penetrate the concretion to determine if there is a real bedrock or another payzone.
Would a hand spun old style drill with a long masonry drill bit be an idea?

Thanks
Reeko