What you said is impossible! You can't buy that kind of ordinary one. There are in the world, but the detection range is only a few meters away and very deep. It's impossible to explore thousands of meters like you said! Moreover, this kind of mine detection device is generally used in the military equipment of developed countries, and ordinary people can't buy it. What we usually use can only measure up and down 10 cm or so, and some will be higher! But if the metal content buried in the ground is high, the signal can also be received. But what you said is just exploring small things, such as gold, silver coins, necklaces and so on! You can't buy a metal detector as demanding as you! You can buy a common one in the market, and then go to places where people often go swimming, such as beaches and rivers, to explore the jewels left by people. Still can make money! We usually use iron metal detectors.

. This is a magnetic induction metal detector. As the name implies, this metal detector can only detect magnetizable metals such as iron, cobalt and nickel, commonly known as needle detector. The accuracy and sensitivity of iron detection are high, and non-ferrous metals such as copper and aluminum with high purity are not detected. So don't be too demanding!