Pyrite — iron disulfide, FeS₂; used as a mineral drug in the calcined and quenched form (煅自然铜)
Nature and flavour. Pungent, neutral. Liver system.
Not a metal in the sense most readers will expect, and not copper despite the name: 自然铜 is pyrite, iron disulfide, the pale brassy mineral that is familiar as fool's gold, and the Chinese name refers to its colour and its being found native rather than smelted. It is one of the mineral drugs, and it is used almost entirely within the trauma and bone-setting tradition: classical sources describe it as dispersing stasis, settling pain and knitting bone, and record it for fractures, for falls and blows, and for the swelling and pain of injury. In that literature it is a formula ingredient rather than a standalone remedy. Modern clinical evidence for these uses is limited and is not established, and the fact that a fracture is being discussed is itself a reason to say plainly that a fracture is an emergency-department matter, not a materia medica matter.
性味归经。辛，平。归肝经。
它既不是多数读者以为的那种金属，也不是铜：自然铜是黄铁矿（二硫化亚铁），即俗称「愚人金」的浅黄铜色矿物；中文名取自其色泽与天然产出而非冶炼所得。它属矿物药，用途几乎完全集中在伤科与接骨传统之内：古籍记载散瘀止痛、接骨疗伤，用于骨折、跌扑损伤与伤处肿痛。在那些文献里它是方中的一味，而不是单用的疗法。上述用途的现代临床证据有限，尚未被证实；而且既然谈的是骨折，就有必要直说：骨折是急诊该管的事，不是本草该管的事。
既是矿物药，安全提示就必须从这一点讲起：矿物不是植物，不因产地条件而标准化，其成分取决于它出自哪个矿体。黄铁矿常与毒砂及其它硫化物矿物共生，未经监管的矿物药材中砷与重金属含量偏高是已有记载的问题，而非假设 —— 中国医学传统内部对矿物药的反对理由，恰恰也是这一条。传统炮制是煅后醋淬；那是按规范执行的生产环节，家庭无法完成，在锅里做点类似的事也不会让材料变得安全。孕期与儿童避免使用；肝肾病患者不宜。骨折需要由临床医师复位与固定，任何矿物都改变不了这一点。本品任何形态都不属于可自行使用之物，须在合格执业者监督下使用。