Where to fossick at an old deep lead mine site?

[Tapdogs1]

Hi guys, I have access to a site on private property where there was a deeplead mine over 100 years ago. Apparently the shaft was 80m deep! It has collapsed in and is just a depression about 1.5m deep. There are a few other holes that were probably shafts as well. I have some old maps too. There are large mullock heaps of smooth river rocks, and a water race that comes from a nearby creek 1km away. There is also the site of either a steam driven pump or the winding mechanism. There is heaps of junk around, bits of rivetted tin, old nails, horseshoes, etc. There is also the site of a stone hut a couple hundred metres away. So my questions are... would I be likely to find gold in the mullock heaps, or should I concentrate on relics?should I dig the mullock heap and spread it out? How do I recognise any particular areas where the gold may have been processed? Any other advice? I am fairly new to this..I have an SDC2300 and a 705. And I know you will want to know where this is....all I can say is 2hrs from Sydney in an old goldfield....thanks!

 

[blisters]

The water would have arrived to a sluice head so I'd look around there and down into the tail race. There would be mullock heaps but are there wash heaps ready to be processed? Some of these mines went dry of water and so there can be unprocessed wash just sitting there. If there is information on how the mine processing was setup then that should go a long way to determine where to look.
Jon

 

[Tapdogs1]

Hi Blisters, thanks for your reply. I thought I replied a while ago but cant find it, I mustnt have pressed the right button...anyway I replied that there is a dam nearby but the race seems to go past it. What would the area at the sluice head look like? If I followed the race to the end that should find it? Also the mullock heaps contain water worn round rocks up to football size, so I suppose stuff piled for washing would be more likely be gravel? I will have another look around and take some photos. The original mine closed eventually due to flooding from ground water but they did get gold before that. I have some info on the company that mined here but not much on techniques they used.

 

[blisters]

A water race might supply water to several mines and have a head race tapped off it to the sluice. But it could also feed the dam and then when full the dam water used to supply water to a sluice at a greater volume and velocity. Given the machinery I would think a sluice would have been built. Keep in mind it could be a ground sluice as well but either way the run off area will give an indication of where to work back up from. There are a lot of variables to give a positive answer as to what your particular circumstance is. Was the deep lead discovered in a creek? It might be a good place to look there also.
Jon

 

[blisters]

This might help explain it, go to page 101 and you'll see there are a few variants of running paywash one of which might be applicable to your situation.
Jon

https://books.google.com.au/books?i...and Mining By S. V. Griffith page 101&f=false

 

[Tapdogs1]

Wow, thank you, that is awesome info! There's no creek, it's just in a paddock, but when it rains a lot (flood rain) the natural flow of water is towards the mine site but then diverts off to one side. The dam is shown on an old map so your suggestion makes sense, that it supplied other mines, as there were several shafts some of which are now on the other side of the nearby road. The whole area is now covered by regrowth which makes it hard to visualise the layout. We're heading there on the weekend so I'll try to draw a plan of the area. I would love to find an old plan in the mining records!

 

[blisters]

...Also the mullock heaps contain water worn round rocks up to football size, so I suppose stuff piled for washing would be more likely be gravel?...

The large stone piles are probably removed from the upper sluice area while the smaller stuff was left to run through the sluice. A pile ready for washing would contain a mixture including the large stones.

That 80m deep shaft you're talking about probably hasn't collapsed in. I'd bet it has been sunk through basalt to reach the deep lead and the shaft is still in tact. The old timers used to timber the top of the shaft and fill it with soil. The subsidence you see might be the timber rotting out so be very careful around any subsidence. Also some shafts are undercut around the hole so don't assume it is safe to go near it unless the shaft is open and you can see its condition.

Your info on the mining company might give you an idea of the size of the gold won and whether you will be able to detect it. Search in trove.nla.gov.au for more company info.

Jon

 

[RedDirtDigger]

Hi Tapdogs, I detect deep leaps on a regular basis. Within hours of Sydney nearly all the deep leads I know are elevated horizontal river channels covered in basalt (the river had lava flow down it covering the gold...the basalt resists erosion and say 12 million years later the basalt usually forms an elevated elongated ridge with the old surrounding hills eroded away (the topography has been inverted/reversed in a 12 million year period). 12-17 million years old is the age of many lava flows/deep leads out from Sydney.

Sometimes the basalt cap can almost be totally removed from above the river bed like on many hills at Ophir.

Not sure what your site looks like but......I would spend some time looking wider around your site. Should be some info on the size of your lead including its extent on the DIGS database (google DIGS).

The river gravel/gold usually comes out the sides/ ends of the ridge in a few places, so try contouring around the ridge at a level below where you believe the shaft hit the gravel. You should walk around the ridge and look for gravel/sediments....then follow it up to the point where it is coming out under the basalt. The ends of ridges on leads are good spot to look for the old stream bed coming out the ends.

There could be gold/gravel tails on the lower slopes that have eroded out of the side of the deep lead that was not concentrated enough for the miners to worry with.

The miners often went straight down from the top to get to the centre/deepest parts of the old river bed as in your case.

Horizontal shafts were commonly dug into the sides of the hill (especially if the basalt cap was thick) to get to the gravel and the slightly uphill mines allowed water to exist easily (water is an issue with many deep leads). Old horizontal mines in deep leads are often hard to find and can have washed in insignificant entrances that look like big wombat burrows. But a good show of gravel will indicate a mine is up slope

Best of luck, RDD

 

[Martin]

I always go through mullock heaps, well worth doing sometimes!