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| Will my magnetometer find Gold? |
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Last Updated
26th of January, 2010
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From our experience there are basically three types of “gold” occurrences: 1) disseminated gold in ore, 2) placer gold that is found in river sediments and 3) treasure which is gold that has been concentrated by human activity and then been lost or hidden. Magnetometers are used to find disseminated gold by its association with mineralized zones which contain magnetite or other magnetic minerals. For ore deposits, magnetometer surveys are often used in conjunction with electromagnetic surveys to find the conductive ore bodies or those that have elevated concentrations of magnetic minerals at a depth of many meters. Placer gold is found in river sediments or ancient stream channels. These sediments originate from erosion in mineralized areas that contained gold bearing ore. In these sediments it is common for gold dust and nuggets to be concentrated in coarse sand and gravel that settles from fast moving water. In addition to gold, magnetite grains are also concentrated in these sands and gravels and it is again the magnetite that provide a magnetic signal that can be used as an indicator of these specific types of deposits. The expectation is that where there is a natural concentration of gold there is often magnetite and therefore a magnetometer survey can be used to locate placer gold deposits.
Gold treasure is a different type of target because it is not necessarily associated with anything that a magnetometer can readily detect. Gold is not magnetic. If gold was buried in an iron or steel container, or buried along with other steel or iron objects then these other objects could provide a indication of the gold's location. Unfortunately, iron or steel objects are very common and are seldom accompanied by gold.
Magnetometers are routinely used to look for treasure ships (Spanish Galleons) and most of the richest finds have been made with high sensitivity magnetometers. The object of the search is typically ballast stones, or ships fittings that give an indication of the area of first impact on a reef. Then the debris trail is followed to find the actual resting place of the valuables. Sometimes hand held diver magnetometers are used to locate iron nails and fittings to give an indication of the debris trail.
The reason that gold is so valuable is that it is rare and that it has no special property that allows it to be detected from a great distance.
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