(There's an eddy swirl behind the big boulder on the right.)
After digressing slightly for Veterans Day, I'm back in the saddle with more on the positive gold potential of obstructions in placer mining. What I'm saying in this series is targeted toward you, the small-scale miner, and not commercial gold miners like those strutting their stuff each week on reality television. You see, a sluice box, highbanker, dry washer, or a suction dredge are vastly different animals than bulldozers, excavators, and wash plants...as are the men and women behind those pieces of equipment. That said, on to obstructions once again.
A Potent Weapon
In most placer mining contexts (wet and dry), I believe that good stream or wash obstructions should rate highly on your mining "to do" list. This is especially true when bedrock or false bedrock is not accessible. Obstructions have been pretty damn good to me (gold-wise, that is) during the course of my checkered small-scale mining career and I've witnessed firsthand just how good they can be to others as well. As I mentioned previously in this series, one of my old-timer mentors "specialized" in working obstructions and he was a master at getting coarse gold and nuggets this way. He didn't employ anything too fancy in terms of gear, just a shovel, hand tools, a sluice box, and on occasion a highbanker. The most potent weapon in his obstruction working arsenal, however, was the simple come along. You see, this old gentleman (and he was that) favored only larger obstructions in terms of the rocks and boulders littering a stream bed and in order to get at the gold behind and underneath those obstructions, he used a come along. In other words, when he found a favorable-looking obstruction that couldn't be moved by hand (and most good ones fall in this category), he simply got to work with that come along and moved that big puppy out of the way. My mentor was very, very good at what he did and he had an accumulation of coarse gold and nuggets to prove it. He was patient, thorough, and hard working (hint, hint) but more than that, he had a sixth sense for knowing where the gold was. He taught me everything he knew about his method of working obstructions, but one thing I never quite picked up was that sixth sense! More's the pity, truth be told.
(Coarse gold and nuggets can be found underneath and behind obstructions.)
Check the Feeder Streams
Anyway, this old timer primarily worked obstructions in secondary streams or creeks feeding into the North Yuba River in the northern part of the California Motherlode gold country. He liked the feeder streams because they were more easily accessible, less powerful in terms of water flow, and ran shallower than the North Yuba. Many of the obstructions dotting these feeders were located to the sides of the stream or creek (nearly dry) or in very shallow water. Add the fact they didn't receive the same amount of attention as the river itself and you have the makings of good obstruction mining. I can vouch for this lack of attention myself since I dredged and highbanked the North Yuba for most of the 1980s. Back then the North Yuba was nearly wall-to-wall with suction dredgers (myself included) but if you took a break and walked along the feeders it was a different world. In fact, during that entire period I NEVER came across anyone else prospecting or mining a feeder, other than myself and my mentor. Yet that old timer often (and sometimes I myself) had the same amount or more placer gold in terms of weight at the end of the day than other miners who'd spent the same hours dredging. The most impressive thing, though, was the amount of coarse gold and nuggets the old timer got in relation to the dredgers.
Putting the "E" into Effort
One thing my mentor taught me about working obstructions was that the best gold was to be found underneath, and not behind them. Thus his remarkable use of the come along. Now some of you are thinking to yourselves that this is all fine and good, but you're also forming the following mental question: "But that was back then and there. Where I like to mine is totally different." Granted, there is truth in this statement because each gold area or locale has its own characteristics and layout. I've seen some gold-bearing streams and washes during my time that really didn't have much in the way of decent obstructions or that were composed primarily of conglomerates or gravels. In situations such as these you're pretty much hosed, truth be told. But if you're working a desert wash with decent obstructions or a running stream with the same, you're missing some potentially rewarding opportunities. One thing I've learned about myself and other small-scale miners over time is that we generally like to take the path of least resistance when prospecting and mining. If something looks too difficult or hard to do, we tend to turn our heads in the direction of what's easier and faster in terms of sampling or gold recovery. Working smarter and not harder is always the way to go, but if you're turning away from obstructions simply because you don't want to put in the effort or hassle, then brothers and sisters you need to reassess yourself as a miner. If that old-timer mentor of mine (who was in his early 70s at the time) could do it, then by God you sure as hell can! Money talks and bullshit walks. Either get with it and do the work or sell off your gear and take up golf.
(Don't want to put forth the effort?)
OK, that said let me finalize this series with a few tips:
1) In desert or dry placers placers work any and all obstructions of merit, REGARDLESS of where they're situated in that arroyo or wash. (I once pulled a quarter troy ounce of flakes and two small nuggets from a half-filled five-gallon of bucket of material taken from behind an obstruction like this in a dry placer close to where I live in Northern New Mexico. Moreover, this obstruction lay in a straight-shot chute, not in a low-pressure area.)
2) While we're on the subject of dry placers, remember that the water flow in them is intermittent at best and subject to violent flash flooding. (This means the gold could be anywhere, even behind or underneath obstructions not "normally" considered viable due to their location in that wash or arroyo...read Number 1) again for proof of the pudding in this regard and think outside the box.)
3) In both wet and dry placers, your best bet is to get underneath that obstruction, not just behind it. (An added bonus here is that if you remove that obstruction you'll end up digging not just underneath it, but all around it. This mean whatever gold was caught up behind the obstruction, along its sides, or even in front of it will likely be recovered by you.)
(Some gold-bearing locations are devoid of obstructions.)
4) Remember that gold tends to get deposited behind obstructions in what I call a "comet's tail" configuration. (The broader part of the comet or "head" is directly below or behind the obstruction and its "tail" will taper off downstream for some distance. This could be a matter of inches or even a few feet or more.)
5) Most obstructions will act as gold traps but not all. (There are no guarantees in mining nor are there in life in general. Sometimes you're gonna hit a dry hole no matter how much work you do.)
6) Buy yourself a come along. (A no-brainer as far as working obstructions is concerned.)
Most of all, have fun out there! (P.S. Nothing against golf, but I'm a miner, not a golfer!)
(c) Jim Rocha (J.R.) 2015
Questions? E-mail me at firstname.lastname@example.org