Properties of goethite and jarosite precipitated from acidic groundwater

Abstract--This study characterizes various chemical and mineralogical properties of goethite and jarosite from a mine drainage nvironment using chemical extraction techniques, X-ray diffractometry (XRD), 57Fe M6ssbauer spectroscopy and scanning electron microscopy (SEM). Goethite and jarosite precipitates were collected from leachate-contaminated soils and from groundwater samples that were stored for up to 3 y. The results indicate that the soil goethites have primarily microcrystalline morphologies with moderately large mean crystallite dimensions (MCD110 ~ 40 nm), and are superparamagnetic at room temperature and magnetically ordered at 77 K. The substitution of A1 for Fe in the goethites is less than 0.03 mol/mol, and there is consequently no measured contraction in the goethite unit cell volume. The jarosite unit cell dimensions, M6ssbauer parameters and chemical compositions indicate that the precip-itates are primarily well-crystallized K-Na-H30 solid solutions, although the presence of poorly crystalline H30-rich jarosite is also identified in one sample