(Some nice-looking concentrates recovered by a New 49er's member.)
In this post I'll be winding things up for you on what to look for in gold-bearing bench gravels. Since this issue came up, I'll also be addressing some methods for working benches. So let's get to it.
Keep your eyes open: Bench gravels aren't always readily visible and at times can be fully or partially hidden by existing overgrowth (wet placers), or alternately, they can be removed some distance from current stream courses or desert washes (dry placers). So the modus operandum here is simply to keep your eyes open and look for what may be unseen or forgotten. In California's northern Motherlode region I came across dozens of benches over the years along feeder creeks and streams that were hidden away from plain sight (overgrown) and took a bit of "eyeballing" to find. So here's the deal with that. If you find a bench like this chances are it hasn't been worked in a while or, if you're incredibly lucky, it hasn't been worked at all. One thing to remember, however, is that some benches (dry or wet) weren't worked simply because the old timers either couldn't get enough gold out of them to make things worthwhile or they contained little to nothing in the way of placer gold in the first place. Like gold mining in general, benches can be a crap shoot but when they're on they can really make your day and then some.
(Oooops! Wrong bench.)
Look for variations of any sort: I've already touched on certain visual clues to look for in benches but allow me the opportunity to stress the following point: the more variation in a given bench, the greater the chance for finding good gold. This is a generalization of sorts on my part but by and large it holds true, both from the gold deposition as well as the visual identifier standpoints. Again, those variations include the variety of:
- Rocks: sizes and shapes.
- Colors: either the entire bench exhibits an "unusual" color such as massive iron oxidation or if layers are present they are distinct from one another in terms of colors.
- Textures: dirts, soils, and sands show a range of textures (thick, thin, granular, gravelly, coarse, etc.)
- Clay or Caliche: variances in color, especially in a localized area.
(Desert caliche...the bane of desert placer miners everywhere.)
Right from the get go there isn't just one way to approach bench gravels. There's no solitary or standard small-scale mining method that you can pull from a book or from the pages of Bedrock Dreams. This may sound a bit like a cop-out but it's not. Each and every bench will dictate to you exactly how it's best dealt with from a mining and gold recovery standpoint. That is, if you've been at this mining thing of ours for a while now. Some bench gravels are fairly easy to knock out, classify, and run. Others require the patience of the biblical Job and/or the endurance of a 1800s-era Chinese coolie laying down track through the Sierra Nevadas for the Southern Pacific Railroad. Some bench material will require puddling...a messy, frustrating, and often time-consuming task. In certain wet placers, benches may be close to or adjacent to a good water source (a true blessing from above) while others may be far removed from that very same water source (you rolled the dice and lost). See what I'm getting at here? No two benches are the same and no two benches will be worked exactly the same way.
Just the same, here are a few tips for working bench gravels:
1. Work as efficiently as possible. Do whatever you can to set yourself up to make the most out of working that bench. If you can set up near water in a wet placer, do so. Can you set up your dry washer right next to that desert bench? Great! Then do it. Can you run bench material through your gear without having to classify or puddle it? Yes? Also good. Can you pump water up (as opposed to carrying it) to where a remote wet placer bench is situated? Will you have to classify and bucket up all that dry bench material and lug it to your dry washer? Are you going to have to hump gas and supplies up to your dry washing site? Should you use your highbanker or sluice box? Or a trommel? (By the way, I don't care what anyone else says on the matter...your motorized [electric or gas-driven] dry washer is the most efficient way of running desert bench gravels). Anyhoo, these questions and dozens of others are what bench gravels present to you as challenges. Your job? Find the easiest, most efficient, and most effective means of working those benches.
(Working a bench and pumping water up to the highbanker.)
2. Work top to bottom, if you can. This is the most logical and safest way to work a bench, regardless of where the pay layers are. Most benches I've encountered (wet or dry) ranged from a low of waist high on up to overhead (remember, I'm over six feet tall) and some were damn scary because they towered over me. I know what you're thinking...how the hell are you going to work a bench that's taller than you are or worse? Here's a two-word answer for you. VERY CAREFULLY! In an ideal bench setting you want to work your way down to a pay layer(s) by knocking the barren crap loose and getting it out of the way as you work your way down. In a bench where gold is scattered randomly in the material from top to bottom, this approach becomes easier and even more logical. However, there will be times when you might have to dig straight into a pay layer or the bench proper because of its overall height. This is risky business and even though I've done it a number of times in my checkered mining career, I don't recommend it for obvious reasons. As an add on here, I always try working from right-to-left or left-to-right as I loosen or dig out bench gravels. That's me though. It really doesn't matter a hoot how you get at those bench gravels as long as you do it as safely as possible. In essence, Ma Nature will intervene here anyway by forcing you to work in terms of the overall size, height, and compositional factors she's put into that bench. Work smart, OK?
(These bench gravels are in Europe, but they present a classic oxidized "wall.")
3. How you work should be a reflection of Numbers 1 and 2. Most benches are pick and shovel jobs and there's no escaping that fact. It's "lift that bale and tote that barge" time. Explosives are out for too many reasons to count, right?! In a wet placer you could always do like the old timers and set up some sort of hydraulic hose (or even use the small one sometimes attached to your highbanker) and blast that bench apart with a water jet, exposing the goodies or channeling them into your sluice box. Just don't get caught by what "Muskrat" calls the "forest Nazis." Them or some dazed and confused tree-hugger who wants to lecture you on the finer points of leftist environmentalism. Oh, and did I mention the fact he just called you a "land raper"? In the first scenario you'll probably get cited and fined by Big Brother's minions. In the latter scenario I suggest you tell that long-haired, dope-smoking ass clown to go ---- himself, all the while fondly patting that 9mm strapped to your hip. Anyhoo, you get the idea.
Oh, by the way...you newbies and greenhorns quit looking so serious out there. I'm only joking (well, kinda sorta).
(c) Jim Rocha (J.R.) 2016
Questions? E-mail me at email@example.com