Altered basaltic tephra from Haleakala, Maui, are characterized using multiple techniques in order to identify the minerals formed under a variety of conditions and understand soil formation processes here. Samples were collected to represent typical bulk weathered material in the crater, as well as solfataric alteration in a hydrothermal environment. For this study X-ray diffraction, electron probe microanalysis, scanning electron microscopy and transmission electron microscopy are coupled with spectroscopic techniques including Mössbauer, visible-infrared reflectance, transmission infrared, and thermal infrared spectroscopies to analyze these samples. The unaltered tephra are composed of feldspar, glass, pyroxene, and olivine. Observed alteration products include iron oxides, phyllosilicates and sulfates, as well as amorphous Al-Si-bearing material. These samples are potential analogs for altered volcanic material on Mars as the pedogenic influences and contact with plants and animals are minimal. Results of this study may help to determine spectral signatures of these samples that could be used for identification on Mars of the minerals observed here.