The examination and characterization of a previously unknown mineral from Alcaparrosa, Chile

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Wakelin, Joshua
Mineral, Alcaparrosa, Chile
In the summer of 2013 while working with Jennifer Day, Dr. Ron Peterson encountered a mineral with an unknown X-ray diffraction pattern. This mineral is pale yellow in colour, fibrous, very light, with a texture similar to cotton candy. With examination of the mineral in Dr. Peterson’s accommodations at the research site the XRD signature of the mineral changed from unknown to that of copiapite. Peterson attributed this to the difference in relative humidity between the location of the mineral discovery and his accommodations where the relative humidity was higher. At Queen’s, experiments were conducted with the mineral using the FEI Quanta 650 FEG ESEM and Fourier transform infrared spectroscopy (FT-IR) in the Avatar 320 detector, as well as an attempt to determine the relative humidity at which the mineral is stable. Several methods of sample preparation were attempted using the Avatar 320 including a diamond press, DRIFT, and transmission methods with varying degrees of success. The experiments did show that the mineral does react when it is exposed to an increased relative humidity, in the range of 5 to 22.5%, and results in a shift of the structure of the sulfate group as seen through a shift in the peaks due to sulfur- oxygen bond adsorption detected with the Avatar 320. The FEI Quanta 650 FEG ESEM also showed a significant change in the physical structure of the mineral when exposed to an increased relative humidity that is not observed with the naked eye. The ESEM also allowed for identification of the chemical composition of the mineral whose main components are S, Si, O, and Fe, with smaller amounts of Mg, Al, and K. The mineral also appears to create sulfuric acid when dissolved in fluids as indicated by respiratory distress of those who handled the mineral at the discovery site. This release of sulfuric acid was noted due the mineral’s light and fibrous characteristics that allowed it to become suspended in the air when disturbed and interact with people in the area. The atomic structure and specific chemical composition of this potentially new mineral is still undetermined.
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