Martian soils and rocks contain a significant fraction of amorphous materials, based on previous lander-based x-ray diffraction and orbital infrared measurements. However, the exact nature and chemistry of the phases that make up this component are not well constrained. The upcoming Mars2020 and ExoMars rovers will carry Raman and visible/near-infrared (VNIR) reflectance spectrometers, offering new methods for characterizing Martian surface materials in-situ. Raman spectroscopy in particular has the potential to discriminate between amorphous phases; however, many of the candidate amorphous phases are absent from Raman spectral databases. We synthesized and spectrally characterized candidate x-ray amorphous phases for Martian soils (amorphous ferric sulfate, allophane, ferrihydrite, allophane with adsorbed sulfate and phosphate, and ferrihydrite with adsorbed sulfate and phosphate) with Raman and VNIR spectroscopy and document the Raman peak locations for these materials. We found that sulfate and phosphate anions were Raman-detectable when adsorbed to allophane, but were not observed when adsorbed to ferrihydrite; a possible cause for this includes decomposition of the adsorbed species during the Raman acquisition. We show that candidate sulfur-bearing species – amorphous ferric sulfate and allophane with adsorbed sulfate – are distinguishable in Raman data. Allophane, ferrihydrite and amorphous ferric sulfate exhibit distinctive VNIR spectra, but are not likely to be distinguishable in the VNIR if mixed with other materials. The potential for detecting adsorbed species is a unique strength of Raman spectroscopy compared to other spectral methods, however further studies are needed to understand the acquisition conditions, abundances and matrix compositions under which adsorbed species can be detected.