SEM-EDX ATLAS OF MINERALS & ROCKS: A BEGINNING

In the past few decades, the scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX) analysis has become more affordable to smaller universities and colleges, which allow students to explore questions of interest. As such, the environment has emerged as a major focus of research in the natural sciences. Current environmental problems such as, climate change, acidification, soil degradation are the product of anthropogenic changes to the Earth’s chemistry reflected in the formation and alteration of minerals. Being able to accurately identify minerals is an essential skill for geoscientist.

The purpose of the proposed book is to provide an updated reference SEM guide to mineral characteristics, identification, and general information. The instrument used for analysis is a Hitachi TM 3030 SEM with a Bruker Quantax 70 Plus EDX. Samples were polished thin and thick sections, and mineral mounts. All images were acquired with the backscatter or secondary detectors. Three different samples were selected to highlight how the technique helps students interpret processes and features. Selected samples are microcline (perthite), rutilated quartz, and a pyroxene andesite. In addition, mineral standards were analyzed for reference chemistry.

The first sample is of perthite that shows zones rich in Na-feldspar and K-feldspar as shown in backscatter, EDX map, and chemistry. Next is rutilated quartz highlighting the contrast in backscatter images between phases due to mean atomic number, determined from chemical analysis. Finally, an andesite shows problems with backscatter analysis because the glass and plagioclase have similar compositions and mean atomic numbers so are identical in backscatter images.

We hope those who may use the proposed book appreciate Earth’s building blocks (minerals) and how they can be used to understand changes that occur, and find new inspiration and insight into the evolving field of mineralogy and global change.