On the composition of martian surface materials

Abstract Observations were made of Mars with the birefringent interferometer. These observations when combined with spectra of the Sun show that Mars has an extremely strong band at 3.1 μ. This band is presumably produced by hydrated minerals on the surface of Mars. A search was also made for the limonite band at 8800 A with a photoelectric spectrometer. This band had a depth which was at most only 2% to 3%. Because of the weakness of this band iron oxides are not considered to be the primary constituent of the surface material.