The White's GMZ
By Chris Gholson
From Page 44
March, 2010 issue of Lost Treasure

With gold prices hitting all time highs in 2009, there has been a marked increase in the number of people wanting to get involved with metal detecting.
Some are simply looking for an enjoyable hobby that will allow them to spend their weekends away from the hustle and bustle of city life. However, a bulk of the interest seems to be coming from those that have felt the effects of the sluggish economy and are searching for ways to supplement their income.
There is also another group that exists which is composed of experienced gold miners that have been greatly affected by the recent ban on dredging passed by the State of California.
Many of these men and women have had to temporarily hang up their dredge nozzles, but most aren’t willing to give up their passion and are looking for other options. At the present time, the most popular option seems to be the metal detector.
I have been involved with metal detecting for over 15 years and can tell you from personal experience it is a great way to get some exercise, fresh air, and experience the wonders Mother Nature has to offer. An added bonus is the distinct possibility of making some extra spending cash.
If you are on the prowl for a new metal detector I’m sure you have discovered by now that the market is bursting with models of all shapes, sizes, and price ranges. With so many choices out there how is a person to decide?
The best way to narrow down your search is by going with manufacturers that have a good track record. One such manufacturer is White’s Electronics based in Sweet Home, Oregon.
For over 50 years, the folks over at White’s have been supplying the public with high quality detectors made right here in the U.S.
One of the newest additions to their lineup is the GMZ. This is a no-frills sort of detector designed specifically with gold hunters in mind.
The unit itself is incredibly lightweight, the controls are straight forward, and it is priced considerably lower than comparable gold machines.
The 50 kHz operating frequency offers heightened sensitivity to small nuggets while still providing reasonable depth penetration.
Without a doubt, one of the best selling points for the GMZ is its ease of use.
Newcomers to the sport will love the fact that there are only three controls. These controls are: Sensitivity, Ground Reject, and lastly, the Ground toggle switch.
The Sensitivity knob is a dual-purpose control. It both turns the unit on and off and also adjusts the Gain, or overall sensitivity. The Ground Reject knob adjusts the ground rejection range, which helps to reduce the effects of mineralized ground. The Ground toggle allows the user to select either Normal or Salt operating modes.
The detector is equipped with a 6” x 10” elliptical DD coil - the same as supplied with the GMT. This coil is an excellent size and will perform nicely for most prospecting applications. It is small and narrow enough to be maneuvered around obstacles, but large enough to actually cover some ground.
The DD configuration also helps ward off a bulk of the ground noise, helping to keep the machine running smooth and stable.
The GMZ features both an external speaker and a 1/4” headphone jack. The speaker is a pleasure to use during the summer time; however, those persons with some hearing loss may find that headphones offer superior audio quality. Be aware that constant use of the speaker may reduce battery life.
It is important to mention that the GMZ is a silent search detector. In other words, there is no constant background hum, or threshold. Therefore, the only sounds that will be heard will either be actual metallic targets or chatter caused by ground mineralization or hot rocks. There are pros and cons to a silent search machine, which we will discuss later.
The GMZ does not have an iron discriminator and, therefore, is considered an All Metal machine. This means that all metal targets, regardless of their composition, will produce an audible response.
Iron discriminators have their place, but, truthfully, I prefer to run all my gold detectors in the all-metal setting. True, this means that more ferrous trash, such as rusty nails and wire, will be dug, but it ensures that no good targets will accidentally be rejected.
Unless a site is heavily contaminated with iron trash, I always opt for all metal operation.

Field Test
The place I chose for the field test was a typical desert creek bed I had come across by chance about two years prior. I remember it was summertime and I had been out detecting most all afternoon and digging nothing but bullets.
I was starting to feel a bit overheated, plus my canteen was running low, so I decided to turn up the creek hoping it would be a shortcut back to my truck, where I knew a jug of ice cold water was waiting.
As I hiked along I began seeing a few stretches of exposed bedrock. I left the detector on and quickly scanned the bedrock as I went.
When I hit the first nugget about a quarter of the way up I quickly forgot about my thirst. Most of the country rock was covered in overburden, however, everywhere it popped up through the gravel I was able to pull gold.
The little creek never yielded anything large, but my lucky shortcut netted me nearly a half-ounce worth of small nuggets.
I had always wanted to revisit the site and see if I had left anything behind. Now that I had the GMZ to test, it offered the perfect excuse for another road trip.
Upon arriving, I was overjoyed to see that two years worth of monsoon rains had done wonders on the creek. The rushing water had shifted the gravels considerably and exposed entirely new stretches of bedrock. I was also glad to see that there weren’t any fresh detector dig holes. It appeared that so far this spot had remained a secret.
My first signal came quickly enough. The baseball-sized rock was actually lying on the surface and, at first glance, I thought I had found a gold-bearing specimen. Unfortunately, when I cracked it in two I spotted the distinctive reddish color of hematite. No gold, just your average run-of-the-mill hot rock.
I spent most of my time on the bedrock, paying special attention to those stretches which looked as if they had just recently been uncovered. The creek had not been trashy to begin with, so I wasn’t surprised by the lack of targets.
After an entire day of detecting I only dug up 12 true metal targets and three more hot rocks. Fortunately, out of the twelve, two ended up being gold.
The first sounded exactly like a slug of lead, but when it didn’t move after kicking away the surface material, I knew it had a chance.
Some three inches later I hit the decomposed bedrock and went down on my hands and knees for a closer look. Using the nose of the coil I was able to quickly pinpoint the object’s location in one of the cracks. I couldn’t help but smile when I swept aside the loose sand and revealed a lovely, butter yellow color. I had found my first nugget with the GMZ!
Later that evening I tossed it on my digital scale; the piece weighed out at 1.3-grams.
The second find for the day came about an hour later from a similar stretch of bedrock. This one was sitting on top and didn’t require any real digging other than a sturdy twig to pry it from its hiding place. Although smaller than the first, it was still a keeper.
My total take for the day was 1.7-grams. Not one of my best hunts, but certainly not one of the worst. Going home with a big, chunky nugget in my pocket would have been nice, but ultimately I accomplished what I had set out to do - prove that the GMZ can indeed find gold.
If the engineers at White’s set out to create one of the industry’s easiest turn-on-and-go gold detectors, then they definitely succeeded. In less than a minute I had the GMZ tuned and was out swinging. Setting up the unit is truly a breeze. I simply placed the Ground toggle switch into the Normal position, turned the Ground Reject knob fully counter clockwise, and finally turned the Sensitivity knob clockwise to the factory suggested preset mark.
The soil at the test site was moderately mineralized, and initially I did experience some feedback as I pumped the coil back and forth towards the ground. This was easily fixed by increasing the Ground Reject setting. When the sound disappeared I knew the machine was ready to go.
It should be noted that continuous noises indicate the detector is not properly ground balanced, and the Ground Reject knob should be turned further clockwise. It is important to keep the machine running smoothly, but never increase the Ground Reject setting more than necessary.
I would suggest that a person try to always run the Sensitivity as high as possible. This will make target signals sound crisper and more distinct, while also increasing overall depth. The downside with a high Sensitivity setting is that it may also amplify ground noise, which can actually mask good targets. In this case, it may actually be beneficial to reduce Sensitivity slightly rather than upping the Ground Reject.
If you find yourself struggling to keep the machine running smoothly, you may want to experiment with the Salt position. This setting provides better stability when working with heavy concentrations of conductive salt or alkali, or if the ground is wet.
I know there are some folks out there that like silent operation detectors, but to be completely honest, I am not one of them. Sure, the constant buzzing of a threshold can be annoying, but that buzz is packed with a lot of valuable information.
Often times a small, or a very deep gold nugget, will not always produce a clear, distinct signal. Many of these subtle targets, which often turn out to be gold, will only trigger a slight waver in the threshold. A silent search detector will likely miss some of these iffy targets; however, they are a lot less fatiguing on the ears. For myself, I don’t mind the extra noise, so if I could have added anything to my wish list for the GMZ it would have been the addition of an adjustable threshold.
My overall impression of the GMZ was positive. As I mentioned before, what impressed me most was its incredibly easy operation. The controls on the GMZ represent simplicity at its finest! There is essentially no learning curve and I feel that even the most inexperienced hunter should be able to master it within an hour.
At only 3.3 pounds (including batteries), the detector can be swung for hours with little fatigue, plus it is compatible with any White’s Goldmaster Series (48-50 kHz) coil. True, I would have liked to have seen an adjustable threshold and a free skid plate would have been nice, but with a retail price of only $499.95, this detector offers good performance at a very reasonable price.
If you are searching for a good quality entry-level gold machine that won’t break the bank, then the White’s GMZ is certainly worth consideration.
To find out more, contact White’s at 1-800-547-6911, or log onto their website at and be sure to mention you read about it in Lost Treasure!
For further information on using a metal detector, visit the author’s website at

The White's GMZ
The White's GMZ

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