Wednesday, February 27, 2013

Gold Sampling: a 3-Phase Plan of Attack (Part3)

 (Hand-dug sample trench. Notice the sample bags in the background.)

Most mining experts agree that each phase of sampling is equally important. I fully understand their perspective, but I beg to disagree a bit. We'll get to why shortly.

PHASE II: SAMPLING

Beating Me to the Punch

In the meantime, some of you have been beating me to the punch here via e-mail and end-of-post comments with questions like, "How do I go about sampling?," "How deep am I supposed to dig?," "What do I use to sample with?," and "How many samples am I supposed to take?"

Metal Detectors
Gold Concentrates
Gold Pans

These are all very fine questions and I heartily commend you for asking them. That said, here's the generic answer to these questions:  

"It varies."

In other words, there's NO "one-size-fits-all" approach when it comes to performing actual gold sampling due to the variables involved.This may sound like somewhat of a cop out, but please believe me when I say it isn't.

What sort of variables? Well, things like:
  • What sort of mining operations are intended (hard rock/lode? placer? large-scale, commercial, individual?).
  • Available resources (time, money, equipment, personnel).
  • Information sought (values per cubic yard or ton, overall mineralization, economic feasibility, and so on).
These are just a few of the variables that can come into play. Essentially, sampling comes down to a series of logical sequences or "explorations" that are meant to divulge specific information that can carry great import and economic impact, from the smallest-scale approach and efforts of an individual miner to the largest and most expensive mining operations in the world.

Most Important Phase

This is why I believe the actual sampling performed is the single-most important phase in the gold sampling process. (Again, this is only my opinion and not holy words from on high etched in stone.)

Anyway, how you sample is dependent in large part on what you're looking to get out of it. If you're an individual miner just trying to get a line of what sort of gold values you can expect along a 100-yard stretch of stream then your approach (and corresponding gear) is going to be vastly different than that of a full-bore commercial operation looking for a bottom line.

 (Core samples like these are typical of commercial or large-scale sampling operations.)

For example as an individual miner you can probably get your sampling needs completed with a few test holes processed with a gold pan, a sluice box, or even a suction dredge. A commercial operation, on the other hand, is probably going to need a series of drill holes or sequenced test pits/trenches. A hard-rock mining operation may require the blasting of numerous rock-wall faces and gathering samples from both vein material as well as adjacent country rock (we'll talk about why later).

No "Magic" Formula

Once again, there are a range of variables that have to be considered when it comes to gold sampling (or mineral/metal sampling in general). My advice? Start thinking outside the box when it comes to sampling. Most importantly, STOP believing there's some sort of tried and true A-B-C formula to sampling that can be applied across the board in any and all contexts. Why? Because there isn't any.

Are there specific approaches, processes, and parameters that can be applied in gold sampling? Sure there are and I plan on discussing a few of those with you in the next post.

Until then, best of luck and stay safe.

If you liked this post, you may want to read: "Gold Deposition in Dry Placers (Part 1)"

(c)  Jim Rocha (J.R.)  2013

Questions? E-mail me at jr872vt90@yahoo.com

4 comments:

  1. Thanks for the great info.....and welcome back!

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  2. You're most welcome my friend. Just got a new home PC up and running today. Best to you, J.R.

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  3. I recently panned 2 5gallon buckets of gravel that I collected off of the bedrock in a dry gulch, and found 0 (zero) colors. my thinking is that gulch has no gold. if it held any gold upstream from that bedrock I would have seen some color, even 1 speck. there's no history of gold from that immediate area either. Am I giving up too easily on that one?

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  4. Well Bo, the old adage applies here I think: "Look for gold where it was found before." Although your prospecting skills may be right on the $$$ (and checking bedrock is always good), if there's no gold or gold mineralization in that area, then you're probably out of luck. Best, J.R.

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