Most of the spectra were obtained from naturally occurring minerals and as a result often show elements that are not present in their chemical formulæ. In cases where the mineral is a member of a solid solution series the spectrum is labeled as being ‘end member rich,’ e.g. Pyrope rich Garnet (page 49) although the end member formula is given. The microscopist can estimate the approximate pyrope percentage based on relative Mg, Ca, and Fe peak heights.
Because of the difference in sensitivities between EDS detectors, it may be useful to compare spectra taken from known samples such as the Smithsonian Institution’s mineral standards. Unless otherwise noted spectra were collected using a 15 keV accelerating voltage.
Most of these spectra were obtained using a detector with a beryllium window, so no carbon or oxygen peaks were recorded. In cases where several different minerals produce the same spectra, this is noted.
KeywordsPhilosophical Magazine High Frequency Spectrum Calcite CaCO Magnesite MgCO
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