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Having been a metal detector hobbyist some years before the advent of discriminators, I was thrilled with their introduction in the 70's. I thought I had arrived when I got my first discriminator, a White's Coinmaster. I sat that detector's discrimination as high as I could go because I was tired of digging pop tops, pull tabs, and aluminum screw caps which abounded in the school yards and beaches of central Florida. Initially, the results were exciting! I was finding more goodies and far less junk. Unfortunately, I did not realize all that I was missing until my nickel count and gold find totals disappeared completely. I then became a student of discrimination and still am today. I would like to share with you some of my knowledge from many years of using discrimination. ™

In a recent article I suggested using the all metal mode or zero discrimination as a means of finding more good targets and bypassing so much of the masking of targets that takes place with all conventional VLF detectors. Here you listen to all targets, learning to discern جهاز كشف المعادن للبيع a good or semi-good tone from all the target tones. This is a time consuming process but using a good test garden can enhance learning this skill. In many trashy environments this is the best possible method of discrimination.

Lowering the sensitivity level on your detector is the only way that I know to increase good target finds in high trash areas as well as finding some targets that are masked by rejected targets. How much depth loss you get depends on the detector. My favorite detectors for lowering sensitivity and still getting good depth are the Fisher brand.

The Fisher 1200 Series of detectors with dual discrimination controls also adds another trick to discriminating. When a target is accepted at the lower discriminate level-indicated by a smooth "buzzing" signal-but changes to a "snap" or "pop" when pressed forward to activate Discriminate 2, the broken signal alerts the operator to the possibility that a nickel, gold coin or ring has been located. But if the same smooth signal is repeated when Discriminate 2 is activated, then the possibility of the target being a penny, clad or silver coin is good. This identifying process can be accomplished in seconds and applies to all metal detectors with two separate discrimation controls.

My favorite discriminating technique is what is termed as "reverse discrimination". This technique can be used with all analogue VLF/TR detectors. Hunt in the VLF all-metal mode and when a target is discovered, pinpoint it to the exact center and place the coil on the soil at that exact point. Without moving the coil, switch the mode to TR and lift the coil from the the soil. If the audio remains the same or decreases you have a good target. If the signal increases in volume when the coil is lifted the target is bad. This explains the reverse designation for this technique, as in analog detectors, good targets will produce volume and bad targets are silent.

A key to enhancing your discrimination with metal detectors that have ground balance controls that are functional in both all metal and discrimination modes, is to make sure you ground balance your detector before adjusting your discrimination. The reason for this is that phase shift takes place in ground balancing and switching into discrimination after ground balancing will avoid any possible phase shift in your discriminator.

Lower your discrimination in almost all treasure hunting environments and yes lower your sensitivity level at the same time. Lower it a little will increase your depth in almost all site areas. Here's to "diggin it"! Larry

Gold is a metal that has a very deep history in almost every culture since the beginning of man kind. It has been described by the Egyptians in their writing over 4000 years ago and was used heavily in their times. It has been used as a money system throughout the world and is seen as a precious metal by most people. The early mining techniques are very intriguing and intuitive.

In early times Egypt was the leading producer of gold stone. They often bragged that in Egypt there was more gold than dirt and it was used extensively in their society. Much of the early gold mining was done by a method of mining called fire-setting. In this method a fire is created against the face of a rock. Once the fire has been burning for a while and the rock is hot, it is doused in water. The shock in the change in temperature causes the rock to break apart. This type of reaction can commonly be seen in glass. If you take a glass straight from the dishwasher, while still very hot, and drop it in a pitcher of ice water it will likely shatter. This principal is referred to a thermal shock and for a less dangerous example you can drop an ice cube into a glass of warm water and watch it crack.

Fire-setting was mostly used in opencast mining, because in underground mines the smoke and fumes tend to linger. This method of mining was frequently used in conjunction with hushing by the Romans. Hushing involves flushing an area with a large volume of water to help reveal veins of mineral ore. Large tanks of water would be built on the top of the hill and rapidly released to expose potential areas that might contain gold. This method required a lot of water and when used in conjunction with fire-setting was used to help carry the rocks and other debris that are created by fire-setting. Hushing is most effective on large steep slopes because it allows the water to build up a tremendous force.

Hushing was also used in combination with undermining by the Romans. Undermining involves digging a passage or shaft below a hill. Wood supports are used to keep the shaft from collapsing. After the shaft is completed, the wooden supports are burned, which causes the shaft to collapse. This results in the hill collapsing on top of it self. Hushing was then used to carry away the dirt and debris and expose any precious metals. Undermining was frequently used during castle sieges to cause walls or towers to collapse as well.

Many of these early methods of mining were discontinued with the advent of explosives and others were improved upon. For instance starting in the 1800's hydraulic mining was used in place of hushing. Hydraulic mining involves using a series of narrowing hoses and pipes to create a very high pressure jet of water that can be used to clear entire hillsides. This is the most devastating type of mining.

The methods used in ancient times for mining in many ways have been improved upon, but in many cases the premise is the same.