An Interview with Minelab Engineer Mark Lawrie
January 2018 by Chris Ralph
The design of metal detectors well-suited for prospecting is an interesting process and not necessarily an easy one to achieve. It is a combination that blends the desires of what prospectors would like, the requirements of sales people and dealers, with the science and physics of what the electronics can achieve.
Without knowing or even thinking about it, I had put together a map that showed me a pattern of the ancient Sacramento River channel. I also had a distinct picture of where the ancient channels of several other creeks and rivers were running.
Across and downstream of our operation was a large pile of huge boulders. It was logical to think that water forces may have deposited gold in and around these boulders. We moved our dredge over and started pulling the rock pile apart.
Over the years that I have been detecting for gold I have had many of the same questions come up. I decided to write this article to hopefully answer some questions that a person wishing to detect for gold may have.
Within this area, about two million ounces of gold and fifty million ounces of silver have been mined. Faults, dikes, veins and fissures that carry the ore form a concentric radial pattern—like spokes on a wagon wheel—around the caldera core.
It was time to prime the pump and start the engine! Dan’s priming method is to use a small, submersible, 12-volt pump. My priming method is to use a hand-operated diaphragm pump.
Pumps can be set up quite a distance away horizontally from the sluice, even hundreds of feet. It will work so long as there is sufficient water at the source where the pump is located. Vertical distance is more of a problem than horizontal distance; 30 to 40 feet is the maximum vertical climb for most pumps.
The Wyoming Geological Survey released an online interactive map...
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