Most of our minerals are purchased through commercial sources, but are often still in the host rock, or exhibit surface contaminants. Because we only want the spectrum of the mineral of interest, we must prepare the minerals via a time-intensive process of crushing, washing, and sieving. Our spectral library is comprised primarily of samples with grain sizes between 710 and 1000 microns (1mm). The mineral samples are then examined by hand, grain by grain, and the impure grains removed. The preparation time for a single sample can be many hours or even days. Once the mineral sample has been cleaned and picked, several grains are removed for electron microprobe and x-ray analysis.
To analyze samples in our lab spectrometer, the grains are poured into small copper cups (shown above).
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