Sem observations of silicate minerals affected by weathering processes

The adoption of multidisciplinary approaches to investigate the interactions between physical and chemical weathering processes and their effects on mineral transformations, has proved to be crucial to shedding light on the weathering profile development. The combination of X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive spectrometer (SEM-EDS) techniques to investigate mica alteration and degradation in weathering profiles has been used to characterize varying degrees of mineral transformation. Regardless of the mechanisms involved, the microscopic investigations indicate that mica grains affected by weathering processes, are locations of intense clay minerals and Fe-oxides formation. The neoformation of clay minerals and ferruginous products replaced feldspars and mica-like minerals during the deeply weathering stage. Qualitative elemental of the secondary product, although including part of the host mica (Si, K, Fe, Ti), indicates an Al-rich mineral phase. Weathered mica grains exhibit expanded edges and exfoliation along cleavage planes, and are commonly covered by clay minerals (e.g., tabular halloysite). Exfoliation and separation of layers along (001) cleavage planes promotes further weathering and transformation into clay minerals (e.g., kaolinite and halloysite) with formation of Fe-oxides. The original structure of the mica minerals is still visible. Furthermore, microfractures and micromorphological variations occur on the original rock fabric. © 2012 Nova Science Publishers, Inc. All rights reserved.