Magnetite is the ore of oxide mineral magnetite. Magnetite, also known as Ci stone, is mostly granular and massive aggregate, and its main feature is iron absorption. The earliest record of the iron absorption performance of magnets in China is the book "Lv's spring and Autumn": "Ci Shi summons iron, or leads it." Lv's spring and autumn was written at the end of the Warring States period, more than 2200 years ago. Qin Shihuang made use of this characteristic to build the North que gate of a Fang palace.
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Compendium of materia medica: CI Shi can cure various diseases of the kidney family, and clear the ears and eyes. A scholar's eyes were often ill, and he gradually felt dark and cloudy. Shi Zhen used the addition and subtraction method of Dongyuan Qianghuo Shengfeng Decoction and served it with Cizhu pills. It was the same in two months. Cover the magnet into the kidney, stabilize and nourish the true essence, so that the divine water does not move outside, cinnabar enters the heart, stabilize and nourish the blood, so that the evil fire does not invade, and assist with Shenqu to digest the stagnant Qi, use both raw and cooked, and warm the Qi of the spleen and stomach. See immortal sun's Qianjin Shenqu pill.