Unformatted text preview: There was a high proportion of Fe and S, the latter some 10-100 times that found in terrestrial rocks. There was some Ca, Al and Si with small amounts of Ti. There was a high Ca:K. There was a high Ca:K ratio. The overal suggestion was of 80% iron-rich clays, 10% Mg 2 SO 4 and 5% each of calcite and higher oxides of iron like haemetite, goethite and maghemite. The material was not dissimilar to what was seen in CI chondrites. The water content was unresolved, but the presence of Goethite is interesting as it is unstable on the surface at daytime and undergoes the reaction 2 FeOOH => Fe 2 O 3 + H 2 O, i.e. it turns into haemetite. Infra-red spectroscopy of the surface suggests the presence of limonite, a mixture of goethite and haemetite, and it has been suggested that this what gives Mars its red colour. There may only be a fraction of this in the surface material, though....
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- Fall '10