Although Iron is the most easily converted material in terms of magnetism, other metal elements are also very magnetic and include Nickel and Cobalt.  Iron and steel alloys are also magnetic    to a lesser degree. Some magnetic alloys contain  Iron, some Steel and some very strong alloys are made from Rare Earth minerals such as Neodymium and Samarium Cobalt. All common materials have a nucleus with electrons in some kind of state. In most materials, the effect of a magnetic field on those electrons is so negligible that it is barely noticeable without the aid of electronic detection devices. Metal detectors use active electrical signals to electronically measure the impact of a magnetic field in order to detect and discern between other metals such as Gold, Copper, Silver and Tin. Materials such as Copper and Aluminium have a unique interaction with magnetic fields which can result in the generation of an electric current.