Mercury’s Mineralogy

Caption NASA:"The top plot shows the ground track of observations made by the Visible and Infrared Spectrograph (VIRS) component of the Mercury Atmospheric and Surface Composition Spectrometer (MASCS). The ground track is projected onto a MESSENGER image of the portion of the planet seen in high-resolution by MESSENGER for the first time.

The bottom plot shows the relative spectral reflectance as a function of wavelength at the two locations indicated on the previous graphic. The visible and infrared portions of the spectra are shown for the two nearby areas, one including ejected material from a bright, relatively young crater and the other from surrounding plains. The two spectra have been shifted vertically to match at 850 nm (in the near-infrared).
Differences between the two spectra, most notable in the infrared, are indicative of differences in the mineral abundances in these two regions".