Tips for Metal Detecting Meteorites
It is best when metal detecting for Meteorites to use a detector with an all metal search mode, that is, do not use discrimination. This is because depending on the size, shape, and nickel content of a meteorite, it can fall anywhere in the discrimination range of a detector. So using any discrimination at all will cause some meteorites to be discriminated out. The smaller a meteorite is, the farther it will be towards the iron end of the discrimination range.
If you don’t have access to an all metal detector for meteorite hunting and want to test a discriminating detector to see how well it does, get some pieces of steel shot about 0.25 inches in diameter. Set the detector discrimination as low as possible and make sure that it can detect the steel shot. Figure that you will be able to detect a meteorite if is at least twice the diameter of the smallest steel shot you can detect. The smaller the meteorite the harder it will be to detect, not just because the signal is weaker, but because it will be lower on the discrimination scale. A meteorite requires a lower discrimination setting than a piece of iron of the same size would because the nickel in the meteorite reduces its conductivity.
The reason that it is important to be able to detect small meteorites is that there are a lot more small ones lying on the ground than large ones. Your chances of ever stumbling across a meteorite the size of a football are rather slim. You have a much better chance of coming across one the size of a golf ball, and an even better chance of finding one the size of a marble.
An all metal pinpoint mode is not the same as an all metal search mode. You need a mode that will automatically readjust the threshold (Auto Tune or Self Adjusting Threshold).
An important consideration in hunting for meteorites is the amount of ground you can cover. While you might find hundreds of coins per acre in a park, the density of meteorites is likely to be much less than one per acre (excluding strewn fields). I estimate that my coil covered approximately 20 acres in all metal mode before I found my first meteorite. To help cover a lot of ground you should have a large coil, but not so large that you cannot swing it for a couple of hours. I would say the 9 to 12 inch range is good.
For a search site you would like someplace uninhabited where meteorites have had a chance to accumulate for thousands of years without being covered up by dirt or being dissolved by water. I would like to hunt the top of a desert plateau. There the winds should blow the dirt off the plateau and keep it from building up and burying any meteorites, and the dry climate would make them last a long time before rusting away to nothing. But if you can’t find the ideal site you should at least look for someplace that is open enough to make full swings of the coil, with sparse enough vegetation to be able to keep the coil close to the ground. You want a place that is free of trash or hot rocks because if you have to keep stopping to dig up pieces of trash you are not going to be able to cover much ground.
I do not have any advice on searching for stoney meteorites because well a metal detector will not find the stoney verity, you will have to rely on eyeball hunting over metal detecting stoney meteorites