Prospecting a hydraulic mine?

[OwenT]

I stopped by a very big old hydraulic area hoping to find some color and just explore what these places are all about. It was very interesting and confusing. First off this place is pretty huge, there's trenches and hills and towers of dirt all over the place. Things that I know to look for were exposed bedrock, places where the sluices might have been, and leftover pay. I walked around for about half an hour, didn't ever see any bedrock, couldn't figure out where a sluice probably was because there were hundreds of little ditches all over the place. I did though in all my time there find one little spot in the wall where a section of ancient river material was exposed, about 1 foot high by 15 feet long, under maybe 4 feet of overburden. To satisfy my curiosity I dry classified some dirt then drove to another site that I was going to pan and panned out 4 little pieces, it looked pretty nice. I'd like to go back and run some more dirt sometime, bad news though is that the only water looked like it came from some very long ditches so it would be really hard to do much testing unless I brought in some water or found a spring maybe. One more thing I noticed is that this mine has like two levels. It's the main hillside they washed away, then it all flattens out into a big area just covered with round piles of rocks, tailing I guess, some are clean, some have a lot of dirt with them, then it goes down again to where all the water runs out. Would they have sluiced just at the main cut or also down below the flat area where all the water leaves?

 

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[KevinInColorado]

I can't help interpret the overall layout of the place but could you drywash the left behind paydirt? That's what I do at the old hydraulic site near me. Test along the upper rim of the area they worked to find more virgin pay they left behind.

 

[Hoser John]

Old pits of the late 1800s were reworked during the depression, reworked after each war and over and over makes for a mess. You posted the main places already...bummer-John

 

[arizau]

To my logic there will probably not be much or any reconcentration of the already washed materials. They obviously moved massive amounts of material and most or all of that material went through sluices where a large portion of the gold was captured. The dynamics of the tailings or waste stream is not the same as the ancient river so any missed gold will now be more mixed than it was in the river channel IMHO. More testing of the probable or possible source(s) of the main activity will probably yield better results for less material moved. If you can transport enough water to fill a black plastic mortar tub then you can process in a "production panning mode"* an acceptable (to me as a desert dweller where I also must carry water) amount of material each trip. As Kevin said, you might try drywashing too.

In any case good luck.

*Pan only to make bulk concentrates for later processing at home.

 

[OwenT]

To my logic there will probably not be much or any reconcentration of the already washed materials. They obviously moved massive amounts of material and most or all of that material went through sluices where a large portion of the gold was captured. The dynamics of the tailings or waste stream is not the same as the ancient river so any missed gold will now be more mixed than it was in the river channel IMHO.

This is what I feared. Well when I get the chance I will probably go with a tub then and do a proper test, unlike my half-pan test I did earlier.

 

[wildminer]

Sounds exciting and fun, though.

 

[Jeff95531]

It is exciting! And fun! And overwhelming I made my first find late last last year and itching to get back...soon as water levels drop enuf. I found wide expanses of bedrock that were seamless and unending. (My rock pick bounced off w/o leaving a mark!) There were truck sized boulders at the bottom of the first level with lotz of BB sized and smaller paydirt in all the openings which are are fist sized or smaller. The tailings pile was 1000 feet long and right next to the creek. The metal detector found only mining parts and NO trash. I'm betting (like you) that they didn't get it all and just might have missed a nugget or two. The history of the mine shows that nuggets and substantial placer was found up until the 20's. Good luck!