Formation of jarosite minerals in the presence of seed material
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Date
2015-03-17
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Volume Title
Publisher
Universities Space Research Association
Abstract
Introduction: There has been a resurgence in interest in jarosite, (K,Na)Fe3(SO4)2(OH)6, and related minerals since their detection on Mars by the MER rover Opportunity [1]. In this context, the presence of jarosite has been recognised as a likely indicator of water at the surface of Mars in the past and it is hoped that study of their formation mechanisms will provide insight into the environmental history of Mars [2]. Jarosites are also of great importance to a range of mineral processing and research applications. For example: they are used in the removal of iron species from smelting processes; they form detrimentally in biometallurgical systems and they are present in acid mine drainage environments. Jarosites are also of considerable theoretical interest as model compounds for spin frustration in Kagomé-Heisenberg antiferromagnetic materials [3]. Knowledge of the formation mechanisms of jarosites is an indispensable prerequisite for understanding their occurrences, stabilities and potential environmental impacts both on Mars and Earth. We are engaged in a program of research to study the nucleation and crystal growth of jarosites under a variety of conditions. Here we report the results of in situ synchrotron powder diffraction experiments designed to follow the crystallisation and growth kinetics of jarosite minerals in the presence of seed materials. Figure 1 shows the structure of jarosite. Layers of blue corner sharing Fe octahedra are connected by yellow sulphate tetrahedra. Cations such as potassium or sodium can also be found in these interstitial layers (red). Jarosite is traditionally reported with
rhombohedral symmetry [3]. However, we have synthesised monoclinic jarosite under certain preparative conditions [4].
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Keywords
Minerals, Crystal growth, Nucleation, Mars planet, Mars space probes, Synchrotrons, Neutron diffraction
Citation
Brand, H. E. A., Scarlett, N. V. Y., & Grey, I. E. (2015). Formation of jarosite minerals in the presence of seed material. Paper presented at the 46th Lunar and Planetary Science Conference, The Woodlands, Texas, USA, 16 to 20 March 2015. Retrieved from: https://www.hou.usra.edu/meetings/lpsc2015/LPSC2015_Program.pdf