1st. are you talking about dredge tailing piles or hand stacked cobble piles left by the Chinese? If Chinese then probably no HG. The two can be hard to tell apart.
Using HG flotation tables inside large bucketline dredges was common practice because it worked very well. The attached pics show the actual HG tables inside one of these dredges. It's really quite amazing. Huge cascading arrays of steel chutes filled with wooden planks which had pockets or channels cut into them were poured full of HG (many gallons). The dredge would scoop the river bottom and run everything through a large trommel or grizzley to reject the oversize. This oversize was run out the back on a conveyor and stacked into piles (house building material) The classified slurry would then be run across sluices to take out the coarse gold and the fines were sent to the tables. The waste from this was run out a separate conveyor. The HG tables would be cleaned up by diverting the slurry off of one table at a time so production would never stop. Yes, a lot of HG was lost.
Now, before you freak out at the potential of a new home becoming a superfund cleanup site...go get some real and unbiased info about mercury. It is not the evil killer of children second only to plutonium that the greenwashed hoard would like you to believe. The toxicity of HG is close to that of Lead and it is a NATURALLY OCCURING element. I would be surprised if any of it found its way to the cobble piles because it would have been lost during the processing of the fines and rejected separately. Bucketline process do vary but even if HG were deposited in the cobbles, it has been subjected to weather and erosion for a century and the liquid metal has long since settled to the bottom of the valley and now rests on bedrock. Even if it were to somehow cling to the cobbles, in the manner you will be using them, you will get a much higher HG exposure by eating a can of tuna.
My advice...build your dreamhouse and please post a pic when you're done, it sounds like an awesome idea!
- Wooden plank with mercury pockets
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- This is only one side of the amalgamation table. If you look to the left you can see where another table slants off to the other side of the dredge.
- IMG_0658 (Large).JPG (112.63 KiB) Viewed 3757 times
- The amalgamation table extends behind the bulkhead from the guy. Total dimension of tables in this dredge is probably 30'x80'
- IMG_0656 (Large).JPG (118.6 KiB) Viewed 3757 times