Spectrometry, Minerals, and Mars: Development of a Lab


Ryuhei Yokokawa

Whitman College, Walla Walla WA 99362


Transmission spectrometry identifies minerals by detecting unique absorption or emission peaks in light of visible and ultraviolet wavelengths (nm). Similarly, satellite-mounted spectrometers measure unique absorption spectra in the reflected light from Mars and Earth enabling researchers to identify and map spatial distribution of minerals. The goal of this project is to develop a lab exercise that demonstrates the conceptual link between laboratory investigation of transmission spectra and a case study of mineral identification by remote sensing. Using the StellarNet EPP2000 spectrometer, geology students will analyze and measure the transmission spectra from 2.5 mm-thick slices of minerals such as fluorite, apatite, and celestite in both UV and visible light. The transparency and the availability of larger samples make these the most suitable minerals. Due to the difficulty in achieving reflected spectra using a UV/Visual spectrometer, transmission spectrometry is used. After data collection, students will evaluate a case study in relation to the spectra of the minerals by examining remotely sensed data from Mars processed using ArcGIS. Students compare the pre-processed ArcGIS map and its geologic context by examining the elevations and locations of olivine deposits. Olivine transforms easily to clay minerals during chemical weathering in the presence of water. Thus, the presence of olivine and its outcrop locations directly relate to the history of water on Mars. The Mars example is intended for understanding reflected spectrometry of a planetary body.