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Diaspores and related hydroxides' Spectral-compositional properties and implications for Mars

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dc.contributor.author Cloutis, Edward A
dc.contributor.author Bell, James F. III
dc.date.accessioned 2018-03-07T16:15:13Z
dc.date.available 2018-03-07T16:15:13Z
dc.date.issued 2000-03-25
dc.identifier.citation 1. Cloutis, E.A., and J.F. Bell III (2000) Diaspores and related hydroxides: Spectral-compositional properties and implications for Mars. Journal of Geophysical Research, 105, 7053-7070. en_US
dc.identifier.issn 0148-0227
dc.identifier.uri http://hdl.handle.net/10680/1396
dc.description.abstract Differences in spectral reflectance properties (0.3-26 μm) of a suite of metal hydroxides (gibbsite, böhmite, diaspore, goethite, and manganite) have been found to be a function of both structural and compositional differences between these minerals. The properties of the O-H stretching fundamental bands in particular can be used to identify the presence of these minerals and to discriminate isostructural and heteromorphous species. This is due to the fact that the O-H stretching fundamental bands are very intense in these minerals and occur at longer wavelengths than those of other minerals, and also due to the fact that these metal hydroxides lack strong absorption bands at shorter wavelengths. In the case of dimorphous minerals such as böhmite (ϒ-A1O(OH)) and diaspore (α-A1O(OH)), differences in the wavelength positions of O-H stretching fundamental bands can be of the order of 0.1-0.3 μm. Reflectance spectra of metal hydroxide-bearing "ores" (bauxites) and impure samples indicate that accessory phases, in particular iron-bearing minerals, have a more pronounced eftect on spectral reflectance toward shorter wavelengths. Intimate mixtures of diaspore + orthopyroxene indicate that diaspore abundances as low as 5 wt% (or less) can be detected by the appearance of characteristic absorption bands at 3.33 and 3.41μm . This finding has particular relevance to the study of near-infrared spectra of Mars, in that the conditions which favor diaspore formation on the Earth may have also been prevalent early in Mars' history. If diaspore did form on Mars in the past, it is likely to have persisted to the present. en_US
dc.description.sponsorship This study was supported by the University of Winnipeg through a start-up grant and research grant through the Discretionary Grants Program (to E.A.C.) and a NASA Planetary Geology and Geophysics Program grant (to J.F.B.; NAG5-4333
dc.description.sponsorship This study was supported by the University of Winnipeg through a start-up grant and research grant through the Discretionary 'Grants Program (to E.A.C.) and a NASA Planetary Geology and Geophysics Program grant (to J.F.B.; NAG5-4333
dc.language.iso en en_US
dc.publisher Journal of Geophysical Research en_US
dc.title Diaspores and related hydroxides' Spectral-compositional properties and implications for Mars en_US
dc.type Article en_US


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