Properties of goethite and jarosite precipitated from acidic groundwater, Dalarna, Sweden

This study characterizes various chemical and mineralogical properties of goethite and jarosite from a mine drainage environment using chemical extraction techniques, X-ray diffractometry (XRD), 57 Fe Mössbauer 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 (MCD 110 ∼ 40 nm), and are superparamagnetic at room temperature and magnetically ordered at 77 K. The substitution of Al 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, Mössbauer parameters and chemical compositions indicate that the precipitates are primarily well-crystallized K-Na-H 3 O solid solutions, although the presence of poorly crystalline H 3 O-rich jarosite is also identified in one sample.