Total-reflectance measurements on a number of igneous rocks and other minerals indicate that reststrahlen features may be of use for remote probes into the nature of the surfaces of the moon and planets. Varying particle size introduces effects such as reduced spectral contrast and in some cases new features that could lead to confusion in identification unless particle size is known. Short-wavelength reflectance measurements offer a method of determining particle size by remote measurements.
W. A. HOVIS, JR. and WILLIAM R. CALLAHAN, "Infrared Reflectance Spectra of Igneous Rocks, Tuffs, and Red Sandstone from 0.5 to 22 µ," J. Opt. Soc. Am. 56, 639-643 (1966)