Magnetite-industrial application is the most important and common iron ore mineral. Titanium magnetite and vanadium-titanium magnetite are also important ore minerals of titanium and vanadium. Rich in titanium, vanadium, nickel, cobalt and other elements, can be comprehensively utilized. Medical magnetite is a famous magnet, which is also called Xuan Shi, Magnetite, Lingshi, Magnetite and Needle Magnetite. Efficacy: subduing yang and calming the nerves; Hear and see clearly; Take a deep breath to relieve asthma. Magnetite is widely distributed and has many causes. Kiruna, Sweden is a typical magmatic deposit. The Laco iron mine in Chile is directly formed by the pulp related to volcanism. The iron ore formed by contact metamorphism can be taken as an example in Daye Iron Mine, China. Iron ore formed by regional metamorphism of sedimentary iron-bearing strata (such as iron ore in Anshan, China) is mainly magnetite and hematite, which is the most important source of iron ore in the world with large scale but low grade. The former Soviet Union, North America, Brazil and Australia all have such large iron mines. Magnetite can also be enriched in riverbed or coastal sand because of its large specific gravity and strong weathering resistance. It can be transformed into hematite after oxidation; If it keeps its original shape, it is called pseudohematite. Magnetite-the most important and common iron ore mineral with medicinal value. Titanium magnetite and vanadium-titanium magnetite are also important ore minerals of titanium and vanadium. Rich in titanium, vanadium, nickel, cobalt and other elements, can be comprehensively utilized. Medical magnetite is a famous magnet, which is also called Xuan Shi, Magnetite, Lingshi, Magnetite and Needle Magnetite. Efficacy: subduing yang and calming the nerves; Hear and see clearly; Take a deep breath to relieve asthma. Magnetism not only has important applications in modern medicine, such as magnetic resonance imaging technology, usually called magnetic resonance CT (computed tomography), but also the application of magnetocardiogram and magnetoencephalography, and it has a long history. In the Historical Records of the Western Han Dynasty (about 90 BC), Cang Gong's biography said that the King of Qi used five kinds of mineral medicines (called five stones) to treat diseases. These five mineral drugs are magnetite (Fe3O4), cinnabar (HgS), realgar (As2O3), alum (potassium aluminum sulfate) and cyanine (2cuCo3). Later generations recorded the application of magnets to treat diseases. For example, in Shennong Materia Medica in the Eastern Han Dynasty (about 2nd century AD), it was mentioned that cold-smelling ci (magnetic) stones were used to treat rheumatism, joint pain, fever, deafness and other diseases. In the medical book Records of Famous Doctors written by Tao Hongjing in the Southern and Northern Dynasties (5 10 AD), it was mentioned that magnets could tonify kidney and strengthen bones, dredge joints, relieve pain and reduce swelling. Sun Simiao, a famous doctor in the Tang Dynasty, also talked about honey pills made of magnets in Qian Jin Fang (AD 652), which can improve eyesight if taken frequently. Sheng Huifang (A.D. 1046) written by He Xiying in the Northern Song Dynasty also mentioned that a magnet can cure children from swallowing needles by mistake, that is, a magnet the size of a jujube pit is polished and put in the throat, and then the swallowed needles are sucked out. Fang Jisheng (AD 1253), a medical book strictly used in the Southern Song Dynasty, also talked about using magnets to treat ear diseases with poor hearing. This is to put a bean-sized magnet in the ear with new cotton, and then put a pig iron in the mouth to improve the hearing of the sick ear. Generally speaking, the medical books of various dynasties often recorded that magnets were used to treat many diseases. Compendium of Materia Medica, written by Li Shizhen, a famous pharmacist in Ming Dynasty, has a rich and summative description of medical magnets. It describes in detail the shape of the magnet, the name of the main treatment, the preparation method of the medicine and various applications. For example, diseases treated by magnets include kidney deficiency deafness, deafness of the elderly, frailty of the elderly, blindness cataract, epilepsy of children, uterine failure, proctoptosis of large intestine, intestinal abscess, abscess bleeding and so on.