Magnetometry

Magnetometry measures in an area the perturbations of the magnetic field caused by contrasts in magnetic susceptibility (where susceptibility is the ability of a substance to take on an induced magnetism caused by its immersion in the Earth’s magnetic field). The magnetic susceptibility of a material (rock or soil) is directly proportional to its iron content, usually in the form of the minerals Hematite (Fe2O3) or Magnetite (Fe3O4). Hence it is only sensitive to ferrous metals. However, iron is often present in accumulations of non-ferrous ores, making Magnetometry a staple in mining exploration and in the archaeological field.