Mossbauer spectra measured by the Opportunity rover revealed four mineralogical components in Meridiani Planum at Eagle crater: jarosite- and hematite-rich outcrop, hematite-rich soil, olivine-bearing basaltic soil, and a pyroxene-bearing basaltic rock (Bounce rock). Spherules, interpreted to be concretions, are hematite-rich and dispersed throughout the outcrop. Hematitic soils both within and outside Eagle crater are dominated by spherules and their fragments. Olivine-bearing basaltic soil is present throughout the region. Bounce rock is probably an impact erratic. Because jarosite is a hydroxide sulfate mineral, its presence at Meridiani Planum is mineralogical evidence for aqueous processes on Mars, probably under acid-sulfate conditions.

https://science.sciencemag.org/content/sci/306/5702/1740.full.pdf

Jarosite and hematite at Meridiani Planum from Opportunity's Mössbauer spectrometer

A revised scheme for the reactivity of iron (oxyhydr)oxide minerals towards dissolved sulfide

Determining the composition of mineral-organic mixes using UV–vis–NIR diffuse reflectance spectroscopy

The remote-sensing approach, using satellite and airborne sensors, is rapidly entering the field of environmental sciences as a complementary tool for studying natural processes. This is mainly because the approach enables an overview of large areas simultaneously, using multiple spectral information that correlates with most of the common land cover compositions, on a temporal basis and in a cost-effective way. In soil science, this technique has shown a potential for determining soil groups, the soil genesis process, and soil degradation, and reflects some soil environment interactions as well. Apparently, the limited spectral information provided by the former sensor did not allow the quantitative remote sensing of soils, and thus it could not be used to benefit the future of such endeavors as “precision agriculture”. Recent technological developments using remote sensing for monitoring the environment have produced a new approach that is able to provide quantitative rather than qualitative information regarding soil status. This approach, namely, hyper spectroscopy imaging (HSR), is characterized by many spectral channels, which expand the spectral information of the sensed material to be analyzed under quantitative approaches. This technique uses a image spectrometer that has been mounted onboard an aircraft and is able to receive discrete information regarding a sensed target from orbit. It has been successfully used in many disciplines, including geology and marine and vegetative studies. Because this technique holds new capabilities, it opens new frontiers in soil applications as well. The capability of soil spectral information to predict several important soil properties has already been demonstrated under laboratory conditions. Under noncontrolled (field) conditions, difficulties associated with the far-distant position of the sensors relative to the target and with the limited ability to sense only the upper soil crust currently prevent the HSR approach from being simply applied to soils. Only a well-designed HSR approach will be able to provide quantitative soil property maps from such far distances. This paper provides a detailed description of the quantitative (spectral-based)approach for assessing soil properties, using the reflectance radiation across the sun 's illumination range along with an extensive discussion of the obstacles (and their possible solutions)preventing this approach from being a pure laboratory equivalent. Also provided is a detailed review of recent work that has concentrated on quantitative soil remote sensing along with a discussion of the future availability of this technology in terms of cost, physical specifications, and possible applications.

Quantitative remote sensing of soil properties

The Moessbauer spectrometer on Spirit measured the oxidation state of Fe, identified Fe-bearing phases, and measured relative abundances of Fe among those phases for surface materials on the plains and in the Columbia Hills of Gusev crater. Eight Fe-bearing phases were identified: olivine, pyroxene, ilmenite, magnetite, nanophase ferric oxide (npOx), hematite, goethite, and a Fe(3+)-sulfate. Adirondack basaltic rocks on the plains are nearly unaltered (Fe(3+)/Fe(sub T) Px), and minor npOx and magnetite. Columbia Hills basaltic rocks are nearly unaltered (Peace and Backstay), moderately altered (WoolyPatch, Wishstone, and Keystone), and pervasively altered (e.g., Clovis, Uchben, Watchtower, Keel, and Paros with Fe(3+)/Fe(sub T) approx.0.6-0.9). Fe from pyroxene is greater than Fe from olivine (Ol sometimes absent), and Fe(2+) from Ol+Px is 40-49% and 9-24% for moderately and pervasively altered materials, respectively. Ilmenite (Fe from Ilm approx.3-6%) is present in Backstay, Wishstone, Keystone, and related rocks along with magnetite (Fe from Mt approx. 10-15%). Remaining Fe is present as npOx, hematite, and goethite in variable proportions. Clovis has the highest goethite content (Fe from Gt=40%). Goethite (alpha-FeOOH) is mineralogical evidence for aqueous processes because it has structural hydroxide and is formed under aqueous conditions. Relatively unaltered basaltic soils (Fe(3+)/Fe(sub T) approx. 0.3) occur throughout Gusev crater (approx. 60-80% Fe from Ol+Px, approx. 10-30% from npOx, and approx. 10% from Mt). PasoRobles soil in the Columbia Hills has a unique occurrence of high concentrations of Fe(3+)-sulfate (approx. 65% of Fe). Magnetite is identified as a strongly magnetic phase in Martian soil and dust.

/pdf/mossbauer-mineralogy-of-rock-soil-and-dust-at-gusev-crater-89wktahwfk.pdf

Mössbauer mineralogy of rock, soil, and dust at Gusev crater, Mars: Spirit's journey through weakly altered olivine basalt on the plains and pervasively altered basalt in the Columbia Hills

Spectroscopic Characterization of Minerals and Their Surfaces: An Overview Thin-Film Elemental Analyses for Precise Characterization of Minerals High-Resolution Transmission Electron Microscopy Applied to Clay Minerals Skeletal Versus Nonbiogenic Carbonates: VN-IR (0.3-2.7- m) Reflectance Properties Photoluminescence, Candoluminescence, and Radical Recombination Luminescence of Minerals Three-Dimensional Thermoluminescence in Minerals Induced Thermoluminescence and Cathodoluminescence Studies of Meteorites: Relevance to Structure and Active Sites in Feldspar Emission of Particles and Photons from the Fracture of Minerals and Inorganic Materials What Excites Triboluminescence? ]5]7Fe-Bearing Oxide, Silicate, and Aluminosilicate Minerals: Crystal Structure Trends in Mossbauer Spectra Crystal Chemistry, Electronic Structures, and Spectra of Fe Sites in Clay Minerals: Applications to Photochemistry and Electron Transport Dissociation and Recombination of Positive Holes in Minerals Variable Oxidation States of Iron in the Crystal Structure of Smectite Clay Minerals Surface Activities of Clays Probing the Surface of Clays in Aqueous Suspension by Fluorescence Spectroscopy of Proflavine Multinuclear Magnetic Resonance Studies of Structure and Dynamics at the Interface of Clay Materials Near-Infrared Correlation Spectroscopy: Quantifying Iron and Surface Water in a Series of Variable Cation-Exchanged Montmorillonite Clays Raman and FT-IR Spectra of the Kaolinite-Hydrazine Intercalate Reactive Cr-O Sites: Catalytic Properties of Chromia-Pillared Montmorillonite and Preliminary Study Results

David F. Blake

Papers

Spectroscopic characterization of minerals and their surfaces