SEARCH · Search NASA
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations
A scheme for the photochemical fixation of water is proposed which involves a five-step reaction sequence; the first step involves the 2 electron reduction of a metal by a coordinated carbonate ligand, with corresponding oxidation of the carbonate to CO2 and O2. Ligand field photolysis of trans- (RH(en)2 H2O CO3) ClO4, and (Rh(en)2 CO3) CLO4 have been studied in the solid state and in aqueous solution at various pH values. Both salts are photoinert in the solid phase, but are quite photoreactive in aqueous solution. In solution, the monodentate ion undergoes efficient isomerization to a mixture of cis and trans - (Rh(en)2 H2O CO3)+, presumably with water exchange. A minor pH increase upon photolysis is evidence of inefficient carbonate (CO3 =) release, with formation of (Rh(en)2 (H2O)2)3+. In contrast, aqueous solutions of the bidentate carbonato complex undergo efficient pH decrease upon ligand field photolysis. Changes in the electronic spectrum (200-500 nm) and pH changes indicate that the desired redox is occurring. The pH increase is due to the aqueous behavior of CO2.
Li2Co(CO3)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Li1+ is bonded to four O2- atoms to form distorted LiO4 trigonal pyramids that share corners with two equivalent CoO6 octahedra, an edgeedge with one CoO6 octahedra, and an edgeedge with one LiO4 trigonal pyramid. The corner-sharing octahedra tilt angles range from 40–82°. There are a spread of Li–O bond distances ranging from 1.98–2.16 Å. Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with four equivalent LiO4 trigonal pyramids and edges with two equivalent LiO4 trigonal pyramids. There are a spread of Co–O bond distances ranging from 2.08–2.17 Å. C4+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.29 Å) and one longer (1.31 Å) C–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Li1+, one Co2+, and one C4+ atom to form a mixture of distorted edge and corner-sharing OLi2CoC trigonal pyramids. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Co2+, and one C4+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Co2+, and one C4+ atom.
Li2Co(CO3)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded in a 3-coordinate geometry to three O2- atoms. There are a spread of Li–O bond distances ranging from 1.93–2.03 Å. In the second Li1+ site, Li1+ is bonded to four O2- atoms to form distorted LiO4 trigonal pyramids that share corners with two CoO6 octahedra, an edgeedge with one CoO6 octahedra, and an edgeedge with one LiO4 trigonal pyramid. The corner-sharing octahedra tilt angles range from 37–84°. There are a spread of Li–O bond distances ranging from 1.97–2.15 Å. In the third Li1+ site, Li1+ is bonded to four O2- atoms to form distorted LiO4 trigonal pyramids that share corners with two CoO6 octahedra and an edgeedge with one CoO6 octahedra. The corner-sharing octahedra tilt angles range from 41–79°. There are a spread of Li–O bond distances ranging from 1.98–2.09 Å. In the fourth Li1+ site, Li1+ is bonded to four O2- atoms to form distorted LiO4 trigonal pyramids that share corners with two CoO6 octahedra, an edgeedge with one CoO6 octahedra, and an edgeedge with one LiO4 trigonal pyramid. The corner-sharing octahedra tilt angles range from 37–82°. There are a spread of Li–O bond distances ranging from 1.96–2.15 Å. There are two inequivalent Co2+ sites. In the first Co2+ site, Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with three LiO4 trigonal pyramids and edges with two LiO4 trigonal pyramids. There are a spread of Co–O bond distances ranging from 2.07–2.19 Å. In the second Co2+ site, Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with three LiO4 trigonal pyramids and an edgeedge with one LiO4 trigonal pyramid. There are a spread of Co–O bond distances ranging from 2.06–2.27 Å. There are four inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.29 Å) and one longer (1.31 Å) C–O bond length. In the second C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.29 Å) and two longer (1.30 Å) C–O bond length. In the third C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.29 Å) and two longer (1.30 Å) C–O bond length. In the fourth C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of C–O bond distances ranging from 1.29–1.31 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Co2+, and one C4+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two Li1+, one Co2+, and one C4+ atom. In the third O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Li1+, one Co2+, and one C4+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Co2+, and one C4+ atom. In the fifth O2- site, O2- is bonded in a distorted T-shaped geometry to one Li1+, one Co2+, and one C4+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Co2+, and one C4+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Co2+, and one C4+ atom. In the eighth O2- site, O2- is bonded in a distorted T-shaped geometry to one Li1+, one Co2+, and one C4+ atom. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to two Li1+, one Co2+, and one C4+ atom. In the tenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Li1+, one Co2+, and one C4+ atom. In the eleventh O2- site, O2- is bonded in a distorted trigonal pyramidal geometry to two Li1+, one Co2+, and one C4+ atom. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Co2+, and one C4+ atom.
Li2Co(CO3)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Li–O bond distances ranging from 1.94–2.13 Å. In the second Li1+ site, Li1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Li–O bond distances ranging from 1.94–2.64 Å. In the third Li1+ site, Li1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Li–O bond distances ranging from 1.94–2.12 Å. In the fourth Li1+ site, Li1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Li–O bond distances ranging from 1.92–2.59 Å. There are two inequivalent Co2+ sites. In the first Co2+ site, Co2+ is bonded in a distorted octahedral geometry to six O2- atoms. There are a spread of Co–O bond distances ranging from 2.10–2.18 Å. In the second Co2+ site, Co2+ is bonded in a distorted octahedral geometry to six O2- atoms. There are a spread of Co–O bond distances ranging from 2.10–2.17 Å. There are four inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. All C–O bond lengths are 1.30 Å. In the second C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of C–O bond distances ranging from 1.29–1.31 Å. In the third C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of C–O bond distances ranging from 1.29–1.31 Å. In the fourth C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of C–O bond distances ranging from 1.29–1.31 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two Li1+, one Co2+, and one C4+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to two Li1+, one Co2+, and one C4+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two Li1+, one Co2+, and one C4+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Co2+, and one C4+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Co2+, and one C4+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Co2+, and one C4+ atom. In the seventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Li1+, one Co2+, and one C4+ atom. In the eighth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Li1+, one Co2+, and one C4+ atom. In the ninth O2- site, O2- is bonded in a 1-coordinate geometry to two Li1+, one Co2+, and one C4+ atom. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Co2+, and one C4+ atom. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Co2+, and one C4+ atom. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one Co2+, and one C4+ atom.
The sample analysis at Mars instrument evolved gas analyzer (SAM-EGA) has detected evolved water, H2, SO2, H2S, NO, CO2, CO, O2, and HCl from two eolian sediments and nine sedimentary rocks from Gale Crater, Mars. These evolved gas detections indicate nitrates, organics, oxychlorine phase, and sulfates are widespread with phyllosilicates and carbonates occurring in select Gale Crater materials. Coevolved CO2 (160 +/- 248-2373 +/- 820 μgC(CO2)/g) and CO (11 +/- 3-320 +/- 130 μgC(CO)/g) suggest that organic C is present in Gale Crater materials. Five samples evolved CO2 at temperatures consistent with carbonate (0.32 +/- 0.05-0.70 +/- 0.1 wt % CO3). Evolved NO amounts to 0.002 +/- 0.007-0.06 +/- 0.03 wt % NO3. Evolution of O2 suggests that oxychlorine phases (chlorate/perchlorate) (0.05 +/- 0.025-1.05 +/- 0.44 wt % ClO4) are present, while SO2 evolution indicates the presence of crystalline and/or poorly crystalline Fe and Mg sulfate and possibly sulfide. Evolved H2O (0.9 +/- 0.3-2.5 +/- 1.6 wt % H2O) is consistent with the presence of adsorbed water, hydrated salts, interlayer/structural water from phyllosilicates, and possible inclusion water in mineral/amorphous phases. Evolved H2 and H2S suggest that reduced phases occur despite the presence of oxidized phases (nitrate, oxychlorine, sulfate, and carbonate). SAM results coupled with CheMin mineralogical and Alpha-Particle X-ray Spectrometer elemental analyses indicate that Gale Crater sedimentary rocks have experienced a complex authigenetic/diagenetic history involving fluids with varying pH, redox, and salt composition. The inferred geochemical conditions were favorable for microbial habitability and if life ever existed, there was likely sufficient organic C to support a small microbial population.
Spectra of Europa reveal a surface dominated by water-ice along with hydrated materials and minor amounts of SO2, CO2, and H2O2. Jovian magnetospheric ions (protons, sulfur, and oxygen) and electrons produce significant chemical modifications of the surface on time scales of a few years at micrometer depths. Our laboratory studies examine the formation and stability of radiation products in H2O-rich ices relevant to Europa. Infrared (IR) spectra of ices before and after irradiation reveal the radiation destruction of molecules and the formation of products at 86 - 132 K. In addition, spectra of ices during warming track thermal evolution due to chemical changes and sublimation processes. IR-identified radiation products in 86 - 132 K irradiated H2O + SO2 ices are the bisulfate ion, HSO4(-), sulfate ion, SO4(2-) and the hydronium ion, H3O(+). Warming results in the formation of a residual spectrum similar to liquid sulfuric acid, H2SO4, for H2O:SO2 ratios of 30:1, whereas hydrated sulfuric acid, H2SO4 4 H2O, forms for ratios of 30:1. Radiation products identified for irradiated H2O + H2S ices at 86 K are H2S2 and SO2. When irradiated at 110 and 132 K, ices with H2O:H2S ratios if either 3:1 or 30:1 show the formation of H2SO4 4 H2O on warming to 175 K. We have also examined the radiation stability of H2SO4. Addition of CO2 to H2O + SO2 ices results in the formation of CO3 at 2046 cm (sup -1) (4.89 m). This is the strongest band from a carbon-containing product in the mid-IR spectral region, and it is also seen when either pure CO2 or H2O + CO2 ice is irradiated. Experiments with CH4 added to H2O + SO2 + CO2 ices addressed the question of methane's use as a marker of methanogens in an irradiated ice environment. New results on the near-IR spectrum of pure H2O2 will be included in this presentation. Interpretations of near-IR water bands, with H2O2 present, will be discussed. Irradiations of H2O2 and H2O + H2O2 mixtures, to examine the possibility of O2 and O3 formation, are currently under investigation and new results will be discussed.
Co3(PO4)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Co2+ sites. In the first Co2+ site, Co2+ is bonded to five O2- atoms to form distorted CoO5 trigonal bipyramids that share a cornercorner with one CoO6 octahedra, corners with three equivalent PO4 tetrahedra, an edgeedge with one CoO6 octahedra, an edgeedge with one PO4 tetrahedra, and an edgeedge with one CoO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 59°. There are a spread of Co–O bond distances ranging from 2.00–2.26 Å. In the second Co2+ site, Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with six equivalent PO4 tetrahedra, corners with two equivalent CoO5 trigonal bipyramids, and edges with two equivalent CoO5 trigonal bipyramids. There are a spread of Co–O bond distances ranging from 2.05–2.23 Å. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three equivalent CoO6 octahedra, corners with three equivalent CoO5 trigonal bipyramids, and an edgeedge with one CoO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 35–53°. There are a spread of P–O bond distances ranging from 1.55–1.57 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two Co2+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Co2+ and one P5+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two Co2+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted T-shaped geometry to two Co2+ and one P5+ atom.
Threshold energy and sunlight photodetachment measurements on negative carbon dioxide ions, using a 2.5 kw light pressure xenon lamp, show that: (1) Electron affinity of CO3(+) is larger than 2.7 e.V. and that an isomeric form of CO3(+) is likely an error; (2) The photodetachment cross section of CO3(-) will roughly be like a step function across the range of 4250 to 2500A, having its threshold energy at 4250A; (3) Sunlight photodetachment rate for CO3(-) is probably much smaller than elsewhere reported; and (4) The probability of having photodetached electrons re-attach to form negative ions is less than 1%. Mass identifying drift tube tests confirm that the slower ion is CO3(-), formed through the O(-) + 2CO2 yields CO3(-) + CO2 reaction.
Carbon is present in various forms in the Earth s upper mantle (carbonate- or diamond-bearing mantle xenoliths, carbonatite magmas, CO2 emissions from volcanoes...). Moreover, there is enough carbon in chondritic material to stabilize carbonates into the mantles of Mars or Venus as well as in the Earth. However, the interactions with iron have to be constrained, because Fe is commonly thought to buffer oxygen fugacity into planetary mantles. [1] and [2] show evidences of the stability of clinopyroxene Ca(Mg,Fe)Si2O6 + magnesite (Mg,Fe)CO3 in the Earth s mantle around 6GPa (about 180km). The stability of oxidized forms of carbon (like magnesite) depends on the oxygen fugacity of the system. In the Earth s mantle, the maximum carbon content is 10000 ppm [3]. The fO2 parameter varies vertically as a function of pressure, but also laterally because of geodynamic processes like subduction. Thus, carbonates, graphite, diamond, C-rich gases and melts are all stable forms of carbon in the Earth s mantle. [4] show that the fO2 variations observed in SNC meteorites can be explained by polybaric graphite-CO-CO2 equilibria in the Martian mantle. [5] inferred from thermodynamic calculations that the stable form of carbon in the source regions of the Martian basalts should be graphite (and/or diamond). After [6], a metasomatizing agent like a CO2-rich melt may infiltrate the mantle source of nakhlites. However, according to [7] and [8], the FeO wt% value in the Martian bulk mantle is more than twice that of the Earth s mantle (KLB-1 composition by [9]). As iron and carbon are two elements with various oxidation states, Fe/C interaction mechanisms must be considered.
Recent airborne thermal infrared observations of Mars from the Kuiper Airborne Observatory (KAO) have provided evidence for the presence of carbonates, sulfates, and hydrates. Using the optical properties of calcite and anhydrite, it was estimated that CO3's and SO4's constituted about 1 to 3 and 10 to 15 wt. percent, repectively of the materials composing the atmospheric dust. Using the derived value as an estimate of total CO3 abundance, and making an assumption that the CO3's were uniformly distributed within the Martian regolith, it was estimated that such a CO3 reservoir could contain roughly 2 to 5 bars of CO2. While the results indicate that several volatile-bearing materials are present on Mars, the observations from the KAO are inherently limited in their ability to determine the spatial distributions of these materials. However, previous spacecraft observations of Mars provide both the spectral coverage necessary to identify these materials, as well as the potential for investigating their spatial variability. This has prompted us to pursue a reinvestigation of the Mariner 6 and 7 infrared spectrometer and Mariner 9 infrared interferometer spectrometer observations. The former data have been recently made available in digital format and calibration of wavelengths and intensities are almost complete. Additionally, we are pursuing the derivation of optical constants of more appropriate carbonates and sulfates.
The infrared spectra of CO frozen in nonpolar ices containing N2, CO2, O2, and H2O and the UV photochemistry of these interstellar/precometary ice analogs are reported. The spectra are used to test the hypothesis that the narrow 2140 cm-1 (4.673 microns) interstellar absorption feature attributed to solid CO might be produced by CO frozen in ices containing nonpolar species such as N2 and O2. It is shown that mixed molecular ices containing CO, N2, O2, and CO2 provide a good match to the interstellar band at all temperatures between 12 and 30 K both before and after photolysis. The optical constants (real and imaginary parts of the index of refraction) in the region of the solid CO feature are reported for several of these ices. The N2 and O2 absorptions at 2328 cm-1 (4.296 microns) and 1549 cm-1 (6.456 microns), respectively, are also shown. The best matches between the narrow interstellar band and the feature in the laboratory spectra of nonpolar ices are for samples which contain comparable amounts of N2, O2, CO2, and CO. Co-adding the CO band from an N2:O2:CO2:CO = 1:5:1/2:1 ice with that of an H2O:CO = 20:1 ice provides an excellent fit across the entire interstellar CO feature. The four-component, nonpolar ice accounts for the narrow 2140 cm-1 portion of the feature which is associated with quiescent regions of dense molecular clouds. Using this mixture, and applying the most recent cosmic abundance values, we derive that between 15% and 70% of the available interstellar N is in the form of frozen N2 along several lines of sight toward background stars. This is reduced to a range of 1%-30% for embedded objects with lines of sight more dominated by warmer grains. The cosmic abundance of O tied up in frozen O2 lies in the 10%-45% range toward background sources, and it is between 1% and 20% toward embedded objects. The amount of oxygen tied up in CO and CO2 frozen in nonpolar ices can be as much as 2%-10% toward background sources and on the order of 0.2%-5% for embedded objects. Similarly 3%-13% of the carbon is tied up in CO and CO2 frozen in nonpolar ices toward field stars, and 0.2%-6% toward embedded objects. These numbers imply that most of the N is in N2, and a significant fraction of the available O is in O2 in the most quiescent regions of dense clouds. Ultraviolet photolysis of these ices produces a variety of photoproducts including CO2, N2O, O3, CO3, HCO, H2CO, and possibly NO and NO2. XCN is not produced in these experiments, placing important constraints on the origin of the enigmatic interstellar XCN feature. N2O and CO3 have not been previously considered as interstellar ice components.
It was found that Ce serves as a chemical tracer of paleo-oceanic redox conditions. It was shown that the unoxidized and soluble Ce(3+) in modern seawater exhibits a negative anomaly relative to the other soluble REE(3+). An expression of soluble Ce(3+) in seawater that was approximately 1900X greater than the average observed in Ce in 600-5000 m Pacific seawater was derived. Since Ce(CO3)(+) and Ce(CO3)2(-) complexes greatly exceed the Ce(PO4) complexes in seawater, the formulations of using carbonate complexes were followed and it was found that the calculated Ce and observed concentrations in the deep 600-5000 m Pacific Ocean agree within the uncertainties of the thermodynamic data. As expected, the calculated Ce concentrations are a strong function of pH and found to be lesser functions of CO3(2-) activities.
In highly alkaline solution, aluminum speciates as the tetrahedrally coordinated aluminate monomer, Al(OH)4- and/or dimer Al2O(OH)62-, yet precipitates as octahedrally coordinated gibbsite (Al(OH)3). This tetrahedral to octahedral transformation governs Al precipitation, which is crucial to worldwide Al production, and to the processing of caustic high-level radioactive wastes. Despite its significance, the transformation pathway remains unknown. Here we explore the roles of atmospheric water and carbon dioxide in mediating the transformation of the tetrahedrally coordinated potassium aluminate dimer salt (K2Al2O(OH)6) to gibbsite versus potassium dawsonite (KAl(CO3)(OH)2). A combination of in-situ attenuated total reflection infrared spectroscopy, ex-situ micro X-ray diffraction, and multivariate curve resolution-alternating least squares chemometrics analysis reveals that humidity plays a key role in the transformation by limiting the amount of alkalinity neutralization by dissolved CO2. Lower humidity favors higher alkalinity and incorporation of carbonate species in the final Al product to form KAl(CO3)(OH)2. Higher humidity enables more acid generation that destabilizes dawsonite and favors gibbsite as the solubility limiting phase. Because the transformation was restricted to occur in thin water films, the results suggest that transition from tetra- to octahedrally coordinated Al does not have to occur in bulk solution, as has often been hypothesized, but may instead appear on the source mineral surface.
Carbonate minerals are germane to questions involving volatile and climate history on Mars [e.g., 1-2]. In particular, the abundance of carbonate-bearing minerals can provide broad useful bounds on the amount of CO2 out-gassed into the atmosphere over its history and their spatial distribution and mineralogy can yield constraints on the environments in which they were produced. Earth-based, orbital, and landed spectral observations provide evidence for the presence of carbonates in the Martian environment [3-6]. Infrared observations made from spacecraft near Mars were interpreted to indicate the presence of carbonates. [6] associated the carbonates with the surface dust and interpreted the mineralogy as being consistent with magnesite (MgCO3). Near- infrared observations from Mars orbit have been interpreted to suggest magnesite outcrops in restricted locations [7-9]. Quantitative estimates of the abundance of carbonates on Mars range from 0-3% [3], 2-5% [6], less than a few percent [10], and <10% [8]. With the growing evidence for magnesite on Mars additional quantitative estimates can be provided via theoretical modeling of the reflectance from the Martian surface. Calcite (CaCO3) and dolomite ((Ca,Mg)CO3) are identified in Asian dust [2-17%], [10] and calcite in Saharan dust [~8-10% [12-15]. The importance of op- tical constants at visible and near-infrared wavelengths as proxies for estimating the effects at infrared wave- lengths, has been investigated [15]. The growing evidence for Mg-carbonates on Mars, the presence of calcite and dolomite in terrestrial aero- sols, and general lack of optical constants for these materials in the visible- to mid-infrared (VMIR, ~0.3-6 ❍m) has motivated the current effort to estimate the optical constants of calcite, dolomite, and magnesite in the VMIR.