Facets of a Martian Olivine
Here are four different views of an olivine grain in Northwest Africa 10645 (a Martian meteorite known as a nakhlite). I photographed the sample using a petrographic microscope, which allows light to pass through minerals to aid in their identification. In the top left, the olivine is imaged using plane-polarized light; to the right of that, it is in cross-polarized light. In the bottom right, the grain is imaged using reflected light. In the bottom left is my own hand-drawn image, focusing on the portions of the grain that I wish to study with quantitative methods. Optical microscopy provides me with qualitative information as to the formation history of these meteorites, and will help place them in the broader magmatic history of Mars.