Characterization of magnetic iron phases in IMPACTITES by MÖSSBAUER spectroscopy

We present the results for two mineral samples from the Natural History Museum (MHN) of San Marcos National University (UNMSM) classified as: potential meteoritic samples coded MHN08 and MHN09 with an iron content of about 10% that were characterized using physical techniques such as energy dispersive X-ray fluorescence (EDXRF), X-ray diffractometry (XRD) and transmission Mössbauer spectroscopy (TMS). This study reveals that the samples consist mainly of quartz, goethite and impactites such as coesite, stishovite, and ringwoodite, and therefore should be classified as impactites. 57Fe Mössbauer spectroscopy allowed the observation of three subspectra, two of them assigned to magnetic iron phases, and a third subspectrum assigned to a superparamagnetic phase. An important contribution of TMS is the possibility of observing this superparamagnetic phase which is assigned to goethite which at RT shows a very broad area (80.8%), and at liquid helium temperature appears as a magnetically ordered sextet.