Wendy M. Calvin 1998 <p><span class="EXLDetailsDisplayVal">There is a long known dichotomy in the martian albedo, with an associated, but mostly assumed, mineralogical split as well. The bright red regions are inferred to be weathered, oxidized dust and the <span class="searchword">dark</span> grey regions unaltered volcanic material. A number of recent analyses suggest this division is unnaturally simplistic and the association of many <span class="searchword">dark</span> regions with the former presence of water requires a re‐examination of the spectra in light of potential alteration minerals. I present an alternate interpretation of the reflectance spectral characteristics of some <span class="searchword">dark</span> regions on <span class="searchword">Mars</span> that includes <span class="searchword">dark</span> layer silicates. If their presence is confirmed on <span class="searchword">Mars</span> this will have implications for sequestration of current and past volatile inventories, clues to the extent and type of geochemical weathering, and potential zones where bacterial life forms <span class="searchword">may</span> have emerged.</span> </p> application/pdf 10.1029/98GL01255 en Wiley Could Mars be dark and altered? article