Quartz vein convergence

[Prospector B]

A question for our new category!

I have two quartz veins separated by around 30 meters both with different levels of gold and mineralisation and geology.
Vein 1 runs NW and appears to be hosted in gneiss rock (hard to break open), the gold is chunky and there is not a lot of mineralisation in the rock.
Vein 2 runs NE and appears to be hosted in green slate, the gold is fine and there appears to be more mineralisation than the first vein.

The foliation of the rocks are all over the shop between the two areas. My question is, if there were a primary reef in the nearby area associated with a bulge could the veins radiate off it? I.E. If I find the spot where the two veins converge could there be a reef there?

Thanks all, B

 

[HeadsUp]

nice question

i dont have the answer

where are the Geotechies ?

 

[richo966]

it is possible but I think it is two different rock formations so different events could have laid them down but you do get good gold where veins cross like x marks the spot so to say worth looking at

 

[Wally69]

Mathematically speaking, if your bearings are correct, the glory point is about 21m walk along any of the quartz lines.

If the actual angle is more acute, it will be a bit further. Another way is to look along the line, pick a tree, move over to the next line and see if you can get a fix on an intersecting landmark.

Well worth the look as the intersection of faults is known to hold good gold loads ( in some circumstances)

Watch out for a deep hole if the scrub is thick, you may not have been the first to follow this theory.

I would love to see a 300oz ingot, good luck.

 

[Barra_Mad]

More info needed just want to clarify that you have slate and gneiss layers that are 30m apart are they at the same altitude, because if so this could be a deformation event on a unbelievable scale. gneiss is a high grade metamorphic rock normally comes out of slate that has been super cooked so to find them in the same area is unusual. Could you please post some photos to add more background???

 

[Prospector B]

Looks like I've goes some exploring to do, unfortunately where the two point meet is more than likely in thick scrub and buried under a few meters of soil.

It's a strange area which I just can't get my head around, wish I was a geologist!

As for someone digging a shaft at the intersection I would not be surprised either, there was mining activity there back in the day and it looks like they cleaned out the creek well, but it's strange they haven't appeared to find these veins... Just another mystery lost to history I suppose.

 

[G0lddigg@]

prospector Barra_Mad is asking because he's studying geology I reckon if you take some time to document your situation you might get a solid response

My understanding of sporadic veins or stringers if they occur seperated like you have explained and hosted from different rock often they can be part of a larger fault or one of the weakest ressure zones for a larger load. Often as pressure surges upwards the downward pressure or weight + gravity forces the silica and mineral solution to find the weakest link and push sideways. This might sound obvious but it sounds to me like you have a really good lead. I'd certainly follow the quartz but expect to loose it a few times, time may be better spent locating the load.

Hope this picture doesn't create more confusion i couldn't find a good picture to explain but imagine that these drill holes are your stringers.

 

[Diggerdude]

A question for our new category!

I have two quartz veins separated by around 30 meters both with different levels of gold and mineralisation and geology.
Vein 1 runs NW and appears to be hosted in gneiss rock (hard to break open), the gold is chunky and there is not a lot of mineralisation in the rock.
Vein 2 runs NE and appears to be hosted in green slate, the gold is fine and there appears to be more mineralisation than the first vein.

The foliation of the rocks are all over the shop between the two areas. My question is, if there were a primary reef in the nearby area associated with a bulge could the veins radiate off it? I.E. If I find the spot where the two veins converge could there be a reef there?

Thanks all, B

Mate you've got chunky gold in quartz, you've already found the reef.

How have you been testing it?

DD

 

[Prospector B]

Thanks all, I'll post up some more info later today. I have quite a few photos of the area and rock which may help to explain the situation but I'll have to go through them.

 

[Diggerdude]

More info needed just want to clarify that you have slate and gneiss layers that are 30m apart are they at the same altitude, because if so this could be a deformation event on a unbelievable scale. gneiss is a high grade metamorphic rock normally comes out of slate that has been super cooked so to find them in the same area is unusual. Could you please post some photos to add more background???

What does the altitude have to do with anything?? Deformation is a 3 dimensional process that can over turn layers/rock types 180 degrees, making altitude irrelevant.
I don't see what's unusual about finding these together either, in areas of high grade metamorphism faulting is common, which often gives you different rocks next to each other.

DD

 

[G0lddigg@]

Hey dd is there not primary amd secondary reefs? I may have misinterpreted the question but thouught prospector b was asking if there is likely a larger lode where this gold was coming from.

 

[Guest]

Having found your lode and ascertained its course, you want next to ascertain its value. As a rule (and one which it will be well to remember) if you cannot find payable metal, particularly in gold "reef" prospecting, at or near the surface, it is not worth while to sink, unless, of course, you design to strike a shoot of metal which some one has prospected before you. The idea is exploded that auriferous lodes necessarily improve in value with depth. The fact is that the metal in any lode is not, as a rule, equally continuous in any direction, but occurs in shoots dipping at various angles in the length of the lode, in bunches or sometimes in horizontal layers. Nothing but actual exploiting with pick, powder, and brains, particularly brains, will determine this point.

Where there are several parallel lodes and a rich shoot has been found in one and the length of the payable ore ascertained, the neighbouring lodes should be carefully prospected opposite to the rich spot, as often similar valuable deposits will thus be found. Having ascertained that you have, say, a gold reef payable at surface and for a reasonable distance along its course, you next want to ascertain its underlie or dip, and how far the payable gold goes down.

As a general rule in many parts of Australiathough by no means an inflexible rulea reef running east of north and west of south will underlie east; if west of north and east of south it will go down to the westward and so round the points of the compass till you come to east and west; when if the strike of the lodes in the neighbourhood has come round from north-east to east and west the underlie will be to the south; if the contrary was the case, to the north. It is surprising how often this mode of occurrence will be found to obtain. But I cannot too strongly caution the prospector not to trust to theory but to prove his lode and his metal by following it down on the underlie. "Stick to your gold" is an excellent motto. As a general thing it is only when the lode has been proved by an underlie shaft to water level and explored by driving on its course for a reasonable distance that one need begin to think of vertical shafts and the scientific laying out of the mine.

 

[Barra_Mad]

Diggerdude I am well aware deformation is 3 dimensional event and this can turn out very different results depending on if we looking at brittle or ductile deformation event which will expose different layers at within the rock structure you don't always get perfect 180 degree folding, also erosion bring altitude into play and add's to the picture. A 30m horizontally can make a world of difference in the rock ages. just look at the yarrowee valley in sabas the rock at the top of the hill is from the is 2.5 million years old and the rock in the valley is 450 million years old so that what altitude has alot to do with it. So I was trying to establish if we where talking about the side of a hill or flat ground and until we have pictures it will be hard to give advice on the situation.

 

[SWright]

G'Day there

I am a geologist and can tell you that it is very very difficult to determine what veins will carry gold, for how long and to what depth. generally we have to sample all outcrops and then drill to get any idea of what is going on. as you rightly said and some other posters have noted, you also need to know what the structure is in the surounding rocks and the rocktype. On what you said it sounds like you have what is called a conjugate vein set that occur roughly at 60 degrees to each other, but this may be distorted by each vein being in different rock types. A geological contact is a very good location for fracturing that may end up hosting veins because of the different way rocks react when strained. A sketch map of the local geology would help. Also remember that gold can also occur as what is called a supergene blanket, where gold can be deposited by recent weathering in the top part of veins and disappear below the water table - the coarse gold sound like that may be happening. Two intersecting veins may result in a shoot being formed and that shoot will plunge down along the vein interection - vertical if both veins are also vertical and or at other angles depending on the intersection angle. If you do a map and PM me I maybe can give you some suggestions.

Araluen

 

[Prospector B]

Thanks for all of the replies, I have heaps to learn 8) Here is some more information, sorry this may be a long post but I will start from the start.

I first thought this area looked interesting because the rocks around the area had a rusty look to them, I first sampled this crevice and got a little gold from it.

Interestingly I found the following intrusion between the bedrock.

I moved up around 5 meters and found this vein, I have previously posted about it here. https://www.prospectingaustralia.com/forum/viewtopic.php?id=4216
Vein 1

Host Rock, the white area is where I have recovered the quartz.

Vein 1's area

To me these rocks look different to the normal slate, they are slightly smoother and harder to get the quartz out of! The vein is in the creekbed and this picture is looking upstream. There are a heap of different quartz veins, and some of them are associated with very green and red rocks, others are like the above pictures. To the right of the creek the hill goes up quite steeply and the foliation in the slate is almost vertical, it is also a grey colour.
Vein 2

Vein 2's area

This area is not to far away from the first and the quarts is on the other side of the first slate outcrop, the distance between the area is around 30m as the crow flies and the altitude would only be a few meters different between the two sites. The direction of the slate has changed direction, in fact as you walk between the two locations the angles of the foliation change a lot.

The amount of gold recovered from this creek is not a lot, less that 1g for a year. But there was some mining activity for over a decade in the area and they never quite found the source of the gold. Vein 1 could be a lode with its chunky gold but I was hoping it would be bigger than a few centimeters across So far I have just been testing with a mallet, cold chisel (not the band) and a dolly pot. Vein 1 had no fine gold in it, just chunks the biggest being a few millimeters long and vein 2 had some fine gold in it, certainly less than vein 1. The area is known for its faults and dyke hosted gold.

mbasko, I kind of understand but not quite. Unfortunately both veins are in the creek bed so I wont be digging too far down, I was hoping I could find an outcrop of the reef up the hillside that is quite steep.

Araluen, is there any particular way to do a sketch map of the geology?

Thanks againall for your help, I hope I have answered some of your questions.

 

[Guest]

Sorry mate for some reason thought you were onto an outcrop on a hill not in a creek bed. Still what I highlighted might still be relevant as I was trying to point out; like Araluen said; that it's very difficult to determine what veins will carry gold, for how long and to what depth without sampling & thinking about the area/layout/direction etc. etc.
You've already confirmed the presence of gold so "Stick to your gold" - don't get caught up in looking to far afield when you are getting gold there. Try to follow it &/or look for those neighbouring lodes/veins that may also hold some gold or lead onto better things? "But I cannot too strongly caution the prospector not to trust to theory but to prove his lode and his metal by following it.........." Unfortunately I don't think theres any quickfire geological way of finding anything else without following what you have already found, whether that be down or up, although there should be some other possible geological or even landform indicators? The geo's might disagree but I'll let them argue about that :lol:
I'm certainly no geological expert just thought that was a good read & insight into it, even if over 100 years old - I think it's still fairly relevant today although our methods, technology, knowledge etc. has certainly advanced over that time.
Good luck with it & hopefully you can get some more gold from around there.

 

[SWright]

G'day

From the photos I can tell two things. the first is that the short lozenge shaped veins are known as en echelon veins. they are an indication of rock movement. Draw a line between the ends of the vein to the next and that will tell you the direction of movement. These type of veins occur when the rock is still quite brittle. You will see another set of en echelon veins where the lines drawn from the ends of those veins are in a direction roughly 60 degrees or so to the first set. These veins are a conjugate set and will always indicate the main movement or a movement associated with a major fault elsewhere. In the Victorian gold mines (slate belt gold) the old timers often found these sets but because of their size were never mined. You can also get lozenge shaped veins - not a part of a set -immediately next to major vein systems and these were known as spurs. They do not lean in the direction opposite to the movement of the shear zone. The second vein looks to me to occur at the intersection of the en echelon set and may constitute a shoot.

These sets and shoots are likely to be very local and not be larger than a few metres at most, but it is an indication that something is going on in the area and as they are gold bearing may mean that the main system is nearby.

To make a geological sketch you will need to get hold of a geological compass - these are different to normal compasses as the east and west are reversed. You need to plot the vein strike and dip (if you can record it) and remember that the direction of the en echelon veins ar not the direction of each of the veins. Map also the rock types, and foliations, dykes and the length of the veins if possible.

araluen

 

[Goldtarget]

Awesome SW, i think I've learnt more in the last two minutes of reading than a few hours left to my own devices, very helpful

 

[20x]

Thanks for all of the replies, I have heaps to learn 8) Here is some more information, sorry this may be a long post but I will start from the start.

I first thought this area looked interesting because the rocks around the area had a rusty look to them, I first sampled this crevice and got a little gold from it.
https://www.prospectingaustralia.com/forum/img/member-images/1408/1402804237_crevice.jpg
Interestingly I found the following intrusion between the bedrock.
https://www.prospectingaustralia.com/forum/img/member-images/1408/1402804302_creviceintrusion.jpg
I moved up around 5 meters and found this vein, I have previously posted about it here. https://www.prospectingaustralia.com/forum/viewtopic.php?id=4216
Vein 1
https://www.prospectingaustralia.com/forum/img/member-images/1408/1402804526_vein1.jpg
Host Rock, the white area is where I have recovered the quartz.
https://www.prospectingaustralia.com/forum/img/member-images/1408/1402804551_vein1hostrock.jpg
Vein 1's area
https://www.prospectingaustralia.com/forum/img/member-images/1408/1402804574_vein1area.jpg
To me these rocks look different to the normal slate, they are slightly smoother and harder to get the quartz out of! The vein is in the creekbed and this picture is looking upstream. There are a heap of different quartz veins, and some of them are associated with very green and red rocks, others are like the above pictures. To the right of the creek the hill goes up quite steeply and the foliation in the slate is almost vertical, it is also a grey colour.
Vein 2
https://www.prospectingaustralia.com/forum/img/member-images/1408/1402804922_vein2.jpg
Vein 2's area
https://www.prospectingaustralia.com/forum/img/member-images/1408/1402804982_vein2area.jpg
This area is not to far away from the first and the quarts is on the other side of the first slate outcrop, the distance between the area is around 30m as the crow flies and the altitude would only be a few meters different between the two sites. The direction of the slate has changed direction, in fact as you walk between the two locations the angles of the foliation change a lot.

The amount of gold recovered from this creek is not a lot, less that 1g for a year. But there was some mining activity for over a decade in the area and they never quite found the source of the gold. Vein 1 could be a lode with its chunky gold but I was hoping it would be bigger than a few centimeters across So far I have just been testing with a mallet, cold chisel (not the band) and a dolly pot. Vein 1 had no fine gold in it, just chunks the biggest being a few millimeters long and vein 2 had some fine gold in it, certainly less than vein 1. The area is known for its faults and dyke hosted gold.

mbasko, I kind of understand but not quite. Unfortunately both veins are in the creek bed so I wont be digging too far down, I was hoping I could find an outcrop of the reef up the hillside that is quite steep.

Araluen, is there any particular way to do a sketch map of the geology?

Thanks againall for your help, I hope I have answered some of your questions.

are you getting much sleep lately mate? :lol:

 

[phil]

20times water anytime you want to head out give us a yell just up the road got all the gear cheers