Limonitum — a mineral drug, an iron-bearing clay and hydrated iron oxide material traditionally identified as limonite, largely goethite mixed with clay and other oxides.
Nature and flavour. Sweet and astringent, neutral. Stomach and Large Intestine systems.
The second of the two mineral astringents, and usually discussed in the same breath as 赤石脂 — the two are the paired drugs of a well-known classical combination whose name is still current in Chinese practice. The sources record it for chronic diarrhoea, for the traditional picture of laxity with bleeding, and in the classical account also for the disorders grouped under vaginal discharge. Its traditional reputation is essentially that of a physical binding and covering agent, and like the other mineral drug its human evidence is limited and is not established. The famous classical pairing is a fact about the literature, not a usage recommendation.
性味归经。甘、涩，平。归胃、大肠经。
两味矿物类收涩药中的第二味，通常与赤石脂并提——两者是一首知名古典方名的成对用药，该方名在当代中医实践中仍在使用。文献记载其用于久泻、古籍所称滑脱不禁伴出血，古典中亦用于带下一类。它的传统声誉本质上是一种物理性的涩固、覆盖作用；与另一味矿物药一样，其人体证据有限，尚未被证实。那个著名的古典配伍是文献事实，不是使用建议。
它是含铁的。血色病或铁过载者不应服用；任何铁负荷相关的疾病者使用前应先咨询。除此之外它带有开采矿物的常规风险：砷、铅等伴生重金属与其它杂质，长期服用即累积性暴露——不应长期服用，且只能使用经检验的材料。作为吸附剂，它会降低其它口服药的吸收，必须与其它药物间隔数小时；正在使用必需药物或窄治疗窗药物者应与药师核对。便秘、大便干结及存在梗阻可能时，涩肠是错的方向。孕期、哺乳期与儿童不宜。古典方剂中两味矿物药同用的场合，矿物暴露的注意事项对两者叠加成立，而不是只对其中一味成立。