We’ve all seen them, walking the beach in sandals and baggy shorts, with their Tilley hats, patterned short-sleeved shirts and pasty white legs, waving their metal detectors back and forth, oblivious to the world.
Perhaps it’s only coincidence that a fair number of them are about two years or so into retirement. Apparently that’s just about how long it takes for some people to become really bored.
As it happens, I’m about two years into what I like to call ’semi-retirement’ and, if the truth be told, I also own a metal detector.
However, don’t expect to see me anytime soon walking along the beach, looking for quarters or anything else someone may have lost.
I use my metal detector to look for gold. Not that I haven’t been pleased to have it in the back of the vehicle when I happened upon the remains of an old miner’s or trapper’s cabin out in the middle of nowhere. My point being that so-called relic/coin metal detectors are also useful tools in locating areas where there is at least some gold. While I have yet to locate a nugget with my detector, I have found areas with concentrations of black sand, small flakes and flower gold. (My approach to prospecting for gold is simply this: it all adds up.)
Different metal detectors work in various ways. The type I own is referred to as a very low frequency (VLF) metal detector. It is a general-purpose detector which contains a coil of wire (wrapped around a circular disk at the end of the handle) known as the transmitter coil. When electricity flows through the coil, a magnetic field is created around the disk. As the detector moves over a metal object, the magnetic field affects the atoms inside the metal. It changes the way the electrons (tiny particles orbiting around the atoms) move. When a metal detector moves over a piece of metal, the magnetic field coming from the detector causes another magnetic field to appear around the metal. It is this second magnetic field, around the metal, that the detector picks up.
The metal detector has a second coil of wire in its head (known as the receiver coil) that is connected to a speaker. As the detector moves over the piece of metal, the magnetic field produced by the metal cuts through the coil. As the detector moves over the metal, electricity flows through the receiver coil, making the loudspeaker beep. The closer the transmitter coil is to the piece of metal, the stronger the magnetic field the transmitter coil creates, and the stronger the magnetic field the metal creates in the receiver coil, the more current that flows to the speaker and the louder the beep.
Now I certainly do not profess to understand a heck of a lot about all the electronic theory that goes into metal detectors, but I do know that the depth at which an object can be located depends on a number of factors such as the size of the metal object and the amount of iron and mineral content in the soil. I also know objects such as pull tabs from beverage cans, coins, nails, metal relics and particles of gold all emit magnetic signatures. Learning to recognize the subtle difference between them can be a challenge.
Most general-purpose metal detectors can locate small objects such as coins to a depth of up to six inches, and larger objects (with higher magnetic signatures) down to a depth of five feet and sometimes more.
General-purpose metal detectors are not typically designed to detect metal objects as small as a particle or flake of gold (maybe half the size of a grain of rice), but they do offer far superior trash metal rejection compared to detectors designed specifically for gold prospecting. Having said that, better quality general purpose detectors usually have a setting which can effectively ‘discriminate’ gold from other metals.
The trick, though, is to remember that “gold is where you find it.”
