Sunday, March 11, 2012

Bench and Field Testing the "Gold Bug Pro" (Conclusion)

(Overall view of area where I conducted my "Gold Bug Pro" field tests.)

Field Testing

The area of New Mexico I chose to conduct my field tests of the "Gold Bug Pro" contains old bucket dredge tailings from sampling work done on the Rio Grande over a century ago. Most of the gold contained in these tailings ranges from microdot flour or flood gold to small and medium-sized flakes. Small nuggets may also be trapped in the tailings but if so, they are probably few and very far between.

Tips for Smart Miners

In light of this fact, I knew the chances of me finding placer gold nuggets or large, coarse pieces was pretty slim. My main intent was to see how my "Gold Bug Pro" functioned in the field under less than ideal conditions and with varying amounts of ground mineralization and the usual amounts of annoying metallic trash.

Small Gold

I began my field tests with the "Gold Bug Pro" operating in "All Metal" mode and using the standard "5" nugget coil that the machine comes standard equipped with. I used this smaller coil rather than my 11" simply because the size of the gold at this location is typically quite small.


(The old tailings contained a range of river rock types and sizes.)

I was able to ground balance the "GB Pro" easily but as soon as I began to sweep the old tailings I began picking up a certain type of hot rock that continually forced me to re-ground balance the machine while operating in "All Metal" mode. Interestingly enough, the "hot rocks" were formed of dark basalt from ancient volcanic activity in this region.

Basalt is not typically thought of as "problematic" when it comes to detecting, but it can contain as much as 15%-25% of iron oxides as well as aluminum in its composition. Whatever the case, the basalt drove me crazy and I had to decrease the sensitivity of the machine to be able to operate effectively in "All Metal" mode.

"Robbing Peter to Pay Paul"

Next I tried operating the "GB Pro" in "Discriminate" mode with my two-digit discrimination value set in the high 30s to about 40. This eliminated the "hot rock" issue for the most part.

However, any time you decrease the sensitivity of a metal detector this way, you'll typically also have a corresponding loss in detection ability, especially with smaller or more deeply buried targets. This "robbing Peter to pay Paul" routine is always a trade off...and it doesn't matter if you're hunting for nuggets or coins or artifacts...it still applies.

Two Things are Needed

Did I find any nuggets or large flakes on my first field test of the "GB Pro?" No, I did not. However, I did find the usual suspects...small pieces of lead shot and bullets which tells me the machine was operating just fine.

There are two things I think I need in terms of finding a bit of gold with the "GB Pro:" 1) a decent area to search (i.e., one known to contain nuggets and coarse pieces) and 2) more experience using this nifty little machine from Fisher.

(Small pieces of lead came out of this hole, but no gold.)

I've been swinging all sorts of metal detectors since the late 1970s and one thing I've learned over time is that it takes a lot of field work to learn the capabilities and limitations of any machine. Based on a very limited test basis, I think the "GB Pro" has a lot of potential...not just for electronic prospecting and nugget shooting, but for coin and artifact hunting as well.

I may be deficient as an electronic prospector or nugget hunter, but that's no fault of this reasonably priced, hot little machine.

Good luck to all of you out there.

If you like this post, you may want to read: "More on Midwestern Glacial Gold (Part 1)"

(c)  Jim Rocha (J.R.)  2012

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

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