Properties of Goethite and Jarosite Precipitated from Acidic Groundwater, Dalarna, Sweden

Roger B. Herbert Jr.
Institute of Earth Sciences, Uppsala University, Norbyvägen 18B, 75236 Uppsala, Sweden

Abstract: 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), 57Fe 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 (MCD110 ∼ 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-H3O solid solutions, although the presence of poorly crystalline H3O-rich jarosite is also identified in one sample.

Key Words: Acid Mine Drainage • Goethite • Groundwater • Jarosite • Mössbauer Spectroscopy • X-ray Diffractometry

Clays and Clay Minerals; April 1997 v. 45; no. 2; p. 261-273; DOI: 10.1346/CCMN.1997.0450214
© 1997, The Clay Minerals Society
Clay Minerals Society (www.clays.org)