Many of the old mining districts were placer mined with large bucket line dredges. They were large floating machinery that churned up the valley floors and mined massive amounts of gravel.
Dredges were notoriously inefficient, relying on the processing volume, rather than efficiency. As a result, there is still a lot of gold left behind in some of the tailing piles. The design of these dredges also caused large gold nuggets and specimens to be lost, as it was screened out and rejected just like any other large rock.
Some of the biggest gold specimens I’ve ever seen were found with metal detectors in tailings.
Learn the History of the Dredged Gold
Not all tailing piles are created equal. Some places have big gold nuggets, other do not. You need to research the mining district you are in and determine if metal detecting is worth your effort or not.
Discriminating Detectors
Tailings are not easy to hunt. They are usually loaded with trash and iron rubbish. Men who worked on the dredge were always tossing out junk as they went along. It can be extra frustrating to metal detect in dredge piles.
To make things easier, I highly recommend a quality gold detector with accurate discrimination
Read: What is the Best Metal Detector for Finding Gold Nuggets?
Hunt Golfball Sized Material and Smaller
Dredge tailings often stretch for miles and miles along a river valley. These piles are not consistent. Some will hold gold and other don’t.
Tailing piles left behind from a bucket line dredge in Oregon.
One thing I have found effective is to detect the piles with smaller material, say golfball-sized and smaller. Since similar size material naturally sorts together over time, you are going to find that the majority of gold nuggets (even big multi-ounce nuggets) will be among this sized material. The big rock piles that are bigger than your head rarely have any gold.
Must Dig Loud Targets
There might be big gold in tailing piles, so you need to be prepared to dig. Don’t avoid those loud “trash” targets that sound like a beer can. You’ve got to dig those if you ever want to find one of those once-in-a-lifetime gold nuggets!
Any metal detector will absolutely “scream” on big nuggets like these. 99% of the time those are going to be trash targets, but you have to dig them if you want to find big heavy gold like this…
Lots of Trash – Less Gold
Even under the best circumstances, you will encounter loads of trash and not much gold. From my experience it isn’t uncommon to hunt for many days between each gold nugget. Just like other methods of gold detecting you will soon realize that most targets are going to be trash. Even with a good discriminating detector you will still have to deal with it.
Big Payoffs
Despite the challenges of hunting tailing piles, it’s worth doing of you have the patience for it. The reason being that the nuggets you will recover are usually good sized. I know several prospectors who focus on hunting tailings, and while they may go days between discoveries, when they do unearth a nugget it is usually are whopper!
Next: Metal Detecting Mine Dumps for Hard Rock Gold