Yu Yu Liang

Yu Yu Liang is the medicinal form of limonite, a naturally occurring amorphous hydrated iron oxide-hydroxide of variable composition usually approximated as FeO(OH)·nH2O, with goethite and lepidocrocite as the principal crystalline phases. The material is a common secondary iron ore formed by the weathering of iron-bearing rocks, gossans over sulfide deposits, and bog-iron environments; the medicinal grade comprises rounded brown to yellow-brown concretions or nodules with a smooth waxy or earthy surface, often hollow and rattling with loose powder inside (the “tai-yi yu liang” concretion form). The nodules are crushed and calcined, then ground to a fine powder for use. In traditional Chinese medicine the prepared mineral is sweet, astringent, and slightly cold, securing the lower jiao to stop chronic diarrhea and uterine bleeding, and astringing leukorrhea, with classical use in formulas such as Yu Yu Liang Wan for prolonged dysenteric disorders.