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#1

22shells
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Joined: 11 September 2014
Posts: 49
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20 February 2016 07:44 am

G'day guys. I've got a question- how did the old timers know exactly where to sink a shaft on a quartz reef? I mean, if you're going to dig a 100ft hole you'd want it to be in the right place, right? It amazes me that they could hit the gold reef many feet below the surface. From what I can gather, they'd pick a reef where surface gold was present- but then how did they know where to dig? And what if surface gold is not present, then how did they do it? Thanks.

4 users like this post: orgone500, Phoenix76, AtomRat, atj14

#2

dwt
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From: Central Vic'ish, VIC
Joined: 20 April 2013
Posts: 1,816
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20 February 2016 08:50 am

Between books I've read, shaft sinkers I've met/worked with, and seeing old shafts re-opened, from what I understand when there is visible gold in a reef on the surface some would sink a shaft directly on top of the reef, it covers costs while your sinking, but that also ruins your chances of digging/recovering any gold in the immediate area around your shaft, one would not want to comprise the top of the shaft by continually digging out the gold around it.
If the reef wasn't visible from the surface and you located it by loaming from a creek then up a hill or incline, the old timers would put in a trench cut (costene) cut which could be any depth to locate the ore body or reef, once they found the reef or ore body and exposed it they could get an idea of what degree it was running at, having enough money to shaft sink outside of the reef/ore body line, and knowing the angle the reef is running on they would then work out how far away from the reef to go to sink a shaft to hit it at a desired depth, it's difficult to explain without drawing pictures but a few things need to be taken into account before shaft sinking, such as ground conditions, angle, dip of reef/ore body.
It was explained to me before how to mathematically (for the life of me I can't remember) work out the angle of a reef and the depth you want to hit it at which would tell you how far away to start your shaft sink,
So for arguments sake lets just say you have found a reef laying on a 50 degree angle, the surrounding ground conditions are good, you want to intersect the reef at 20 meters down vertically, so you may have to move 10 meters up hill to sink the shaft, if the reef/ore body is running North / South and dipping (laying) to the West, then can sink your shaft on the Eastern side, this brings into play hanging walls and foot walls, hence looking at ground conditions, if your underground looking at a reef line running north and your facing north and the ore body is laying across to the west, then host rock on your right or eastern side is classed as the hanging wall and the host rock on the western side of the ore/reef body is your footwall.
Sinking directly on top of the ore body can be done if your ore body is vertical, if it is on an angle then your shaft is going to have to follow that same angle, this can lead to hanging wall failures, resulting in the loss of your shaft, trapping underground workers or worse, death.
Hope this helps mate, smile


swing it..dig it...wash it...pan it...LOVE IT..

6 users like this post: Phoenix76, AtomRat, atj14, silver, MJB, Billy

#3

AtomRat
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From: Katazone, VIC
Joined: 22 May 2014
Posts: 5,002
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20 February 2016 08:58 am

Following the breadcrumbs of gold 22shells smile

First determine if gold is on the surface, then by loaming find the source of where the golds coming from, like a quartz reef. Most the time the main quartz reef needs to be intersected by indicator veins followed by crossveins that deposit gold near the intersecting veins. I'm sure the first blokes who attempted it, did have a lot of loss until the Cornish miners came over. They find that gold is in an area and carefully determine the best way to attack a load. They found hitting the load from the top was time consuming or wasteful, they started to sink a shaft a few feet or meters away from the vein or outcrop, dig a verticle shaft hopefully not hitting the quartz, and then using drives to gain horizontal access to the load where they could then stope it out, in an organised fassion to reduce collapse and loss.

I have a lot to learn still, but I gather this is close to how they removed a quartz load specifically. In their drives they could chase 'stringer' veins leading them to a deeper deposit..etc. Alluvial shafts were the easy grabs..dig a hole to bedrock and scrape

Last edited by AtomRat (20 February 2016 09:05 am)


Wisdom is knowing how little you know

2 users like this post: dwt, silver

#4

dwt
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From: Central Vic'ish, VIC
Joined: 20 April 2013
Posts: 1,816
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20 February 2016 09:12 am

AtomRat wrote:

In their drives they could chase 'stringer' veins leading them to a deeper deposit..etc. Alluvial shafts were the easy grabs..dig a hole to bedrock and scrape

We're still doing that nowadays AR, in small scale, if the diamond drillers aren't going to drill in that area, stringers are marked up by geo's and if and when the ore body were following pinches out we go back to the stringer bore probing or sludge holes and then kick off a splay drive if the ore body carries any weight,
Good post mate wink


swing it..dig it...wash it...pan it...LOVE IT..

1 user likes this post: AtomRat

#5

AtomRat
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From: Katazone, VIC
Joined: 22 May 2014
Posts: 5,002
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20 February 2016 09:16 am

Trying to summarise it as best as I can just as you did dwt haha yeah I know where some auriferous ones are I'd like to dig...

Couldn't get this any clearer, in the first pic, the shaft is the vertical doubles lines in the center of the pic
1455920173_14559200164950.jpg

1455920397_14559203477251.jpg

Last edited by AtomRat (20 February 2016 09:32 am)


Wisdom is knowing how little you know

2 users like this post: Chewy, 22shells

#6

22shells
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Joined: 11 September 2014
Posts: 49
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20 February 2016 11:52 pm

Thanks dwt and AtomRat! Much appreciated and very interesting. I have come across some of those costene trench cuts, cutting through quartz reefs. Some about a meter deep and some only a foot deep. What they did back then would still work today.

#7

Roscoe
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From: , QLD
Joined: 27 October 2013
Posts: 742
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21 February 2016 12:11 am

Good question 22shells and one that i was asking myself lately. Its good to know what the old boy's were up to out there and this makes sense in what you see in your travels on the goldfields. Here is an interesting piece out of Ion L. Idriess book Prospecting for gold "If you are a "leader-chaser" you will crush your own stone with a spring dolly... A Leader is a small reef, say, up to eighteen inches wide. Some leader chases are Aristocrats. They will only chase "specimen" leaders. A specimen leader is one in which the stone makes rich patches of specimen gold. The "Chasers" dolly the specimens in a hand dolly-pot and leave the rest of the leader..."

So from his writings its interesting to Note that these leader chasers left the leader after dolling all the rich stone on the surface and left to find more of the like. If this is true then it would of made it very difficult for someone to come behind them and find the leader again. This sound familiar with metal detectorists today, they find a few specimens and never look for the source or dig down on these leaders. They possibly could be leaving a fortune behind?

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