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All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Adrianite, Ca12(Al4Mg3Si7)O32Cl6, a New Cl-rich Silicate Mineral from the Allende Meteorite: An Alteration Phase in a Ca-Al-rich Inclusion

Adrianite (IMA 2014-028), Ca12 (Al4Mg3Si7)O32Cl6, is a new Cl-rich silicate mineral and the Si, Mg analog of wadalite. It occurs with monticellite, grossular, wadalite, and hutcheonite in altered areas along some veins between primary melilite, spinel, and Ti, Al-diopside in a Type B1 FUN (Fractionation and Unidentified Nuclear effects) Ca-Al-rich inclusion (CAI), Egg-3, from the Allende CV3 carbonaceous chondrite. The mean chemical composition of type adrianite by electron probe microanalysis is (wt%) CaO 41.5, SiO2 27.5, Al2O3 12.4, MgO 7.3, Na2O 0.41, Cl 13.0, O=Cl –2.94, total 99.2, giving rise to an empirical formula of (Ca11.69Na0.21) (Al3.85Mg2.88Si7.23) O32Cl5.80. The end-member formula is Ca12 (Mg5Si9) O32Cl6. Adrianite has the I43d wadalite structure with a = 11.981 Å, V = 1719.8 Å3, and Z = 2, as revealed by electron backscatter diffraction. The calculated density using the measured composition is 3.03 g/cm3. Adrianite is a new secondary mineral in Allende, apparently formed by alkali-halogen metasomatic alteration of primary CAI minerals such as melilite, anorthite, perovskite, and Ti,Al-diopside on the CV chondrite parent asteroid. Formation of secondary Cl-rich minerals sodalite, adrianite, and wadalite during metasomatic alteration of the Allende CAIs suggests that the metasomatic fluids had Cl-rich compositions. The mineral name is in honor of Adrian J. Brearley, mineralogist at the University of New Mexico, U.S.A., in recognition of his many contributions to the understanding of secondary mineralization in chondritic meteorites.

Adrianite↗
NASA NTRS2019

Grossite-Rich Refractory Inclusions in Carbonaceous Chondrites: Evidence for Early Generation of Different O-Isotope Reservoirs in the Protoplanetary Disk and O-Isotope Exchange During Fluid-Rock Interaction

The oxygen isotopic composition of the Sun inferred from the measurements of the solar wind returned by the Genesis spacecraft is O-16-enriched (△O-17 = -28.4±3.6‰) relative to the whole-rock O-isotope compositions of chondrites and achondrites, and chondrule phenocrysts, which all plot close to the terrestrial fractionation line (△O-17 ∼ ±5‰). Vast majority of refractory inclusions (CAIs and AOAs) in carbonaceous chondrites of petrologic types 2-3.0 are iso-topically uniform and have solar-like △O-17. In contrast, CAIs and AOAs in metamorphosed CV and CO chondrites are isotopically heterogeneous with melilite, anorthite, perovskite, Zr- and Sc-rich oxides and silicates, and occasionally Al, Ti-diopside being O-16-depleted relative to hibonite, spinel, Al-diopside, and forsterite. The timing of generation of different O-isotope reservoirs and the nature of O-isotope heterogeneity in refractory inclusions in CO3 and CV3 chondrites are poorly known. Grossite (CaAl4O7) is one of the first minerals predicted to condense from a gas of solar composition and therefore it could have recorded isotopic compositions of reservoirs during the earliest stages of the Solar System evolution. Here we report on O-isotope compositions of grossite-rich CAIs in CH3 and CO3 chondrites measured in situ with the UH Cameca ims-1280. For analytical procedures see [9].

A N Krot↗
NASA NTRS2023

The H Content of Aubrites: An Evaluation of Bulk Versus in Situ Methods for Quantifying Water in Meteorites

Aubrites and enstatite chondrites (ECs) are isotopically similar to the Earth and therefore may resemble the primary materials that accreted to form our planet. Recent bulk H elemental and isotopic analyses of ECs and the Norton County aubrite suggest that enstatite-rich materials are H-rich and may represent a significant source of terrestrial water, with measured values of 3000±2000 μg/g H2O and 5300±900 μg/g H2O in the bulk and enstatite fractions of Norton County (Piani et al., Science, 2020). Here, we present a detailed investigation of in situ H2O concentrations in enstatite, diopside, forsterite, and plagioclase from a suite of main group aubrites, including Norton County, and Shallowater. We find that enstatite (4±2 μg/g H2O), diopside (4.8±0.5 μg/g H2O), and forsterite (5±3 μg/g H2O) have similar H2O concentrations, and all are significantly lower than plagioclase (24±3 μg/g H2O). We combine our in situ analyses of H2O contents with equilibrium partition coefficients and bulk mineralogies to estimate the bulk H2O content of our samples. We compare these first order estimates with bulk volatile analyses conducted using sample pyrolysis and find that the previous bulk H2O analyses of aubrites predominantly reflect terrestrial contamination and alteration. If our conclusion that the reported bulk H2O analyses of Norton County primarily reflect terrestrial contamination and alteration extends to bulk analyses of ECs, then EC-like material may not be a significant source of terrestrial water. Our results support the hypothesis that thermal metamorphism, melting, and differentiation leads to efficient desiccation of planetesimals relative to chondrites, and that differentiated planetesimals contributed, at most, trace amounts to Earth's water budget.

Achondrite↗
DOE OSTI2024

Geochemical-hydromechanical couplings during water-serpentinized harzburgite interactions at 20° C and 30 bars

Interaction of groundwater with the serpentinized harzburgites of the upper mantle plays an important role in the geologic carbon cycle and serpentinization processes. Here, in this study, an intact serpentinized harzburgite with more than 60% lizardite from the Semail ophiolite in Oman was reacted with water at near neutral pH and low PCO 2 to observe its dissolution behavior and reaction path within the CaO-MgO-SiO 2 -CO 2 -H 2 O system at 20 °C and 30 bars. In the experiment, mass (i.e. H 2 O, ions) transfer is by diffusion and the selected temperature and pressure conditions mimic water-rock interactions at the shallow portions of most ultramafic rock hosted aquifers. Equilibrium activity-activity diagrams and thermodynamic data were used to compare the experimentally determined reaction path with the theoretical stability boundaries for minerals involved to investigate the evolution of bulk chemical composition, mineralogy, and water composition. The experiments demonstrated that (i) the water-rock interactions increased the pH of the aqueous phase from 5.9 to 7.5 over a period of 18 weeks; (ii) the dissolution of lizardite, orthopyroxene (enstatite), and clinopyroxene (diopside and augite) increased the concentration of Mg, Ca, and Si in the aqueous phase; (iii) the dissolution was incongruent with respect to Mg and Si, favoring Si release at pH > 6 due to (a) breaking of more reactive cation‑oxygen bonds that is consistent with the stoichiometry of magnesium for proton exchange reaction which favors a surface that is enriched in Mg at basic conditions, and (b) preferential dissolution of clinopyroxene Mg 1.30 Ca 0.52 Fe 0.06 Si 2 O 6 ; (iv) the aqueous phase was undersaturated with respect to carbonate (e.g. calcite, magnesite, and hydromagnesite) and hydrous (e.g. lizardite, chrysotile, brucite, and talc) minerals; (v) the bulk chemical composition and mineralogy of the intact serpentinized harzburgite matrix did not change; (vi) the thermodynamic data can successfully predict water-intact serpentinized harzburgite behavior if the water chemical composition can be constrained; and (vii) no detectable macroscopic form of damage (e.g. microcracks forming as a result of differential stress fields due to changes in volume during chemical reaction) was observed.

Carbonation↗
DOE OSTI2025

Anthropogenic Influences on the Chemical and Mineral Composition in Pond Sediment by X-Ray Absorption Spectroscopy and X-Ray Powder Diffraction

Manmade detention ponds have historically been impacted by anthropogenic activities such as rainwater runoff, car emissions, and drainage from infrastructures, which can lead to complications for pond ecosystems. Sediment samples collected from the northern, southern, western, and eastern regions of a small pond on a suburban high school campus on Long Island, NY, were analyzed for potential chemical changes resulting from an inundation of water by a broken water main. Incorporating synchrotron X-ray techniques, sediment was analyzed using Submicron Resolution Spectroscopy, Tender Energy X-ray Spectroscopy, and X-ray Powder Diffraction to examine heavy metals, light elements, and minerals. Results include a Zn:Cu ratio increase from 4:1 to 10:1 in the eastern zone and a higher heavy metal presence in the western zone for all elements examined, with greater distribution throughout the pond post-inundation. Lighter elements appear to remain relatively unchanged. The appearance of diopside in the eastern zone post-inundation samples suggests contamination from the water main break, while the presence of carbonate minerals in the western zone is consistent with erosion of asphalt material from the adjacent parking lot.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1971

Hibonite, Ca2/Al, Ti/24O38, from the Leoville and Allende chondritic meteorites.

Hibonite was discovered in light-colored, Ca-Al-Ti-rich and Si-Fe-poor, achondritic inclusions of the Leoville and Allende HL-group chondrites. Two varieties of hibonite occur: one emits a bright red-orange luminescence under electron bombardment and has high amounts of Al2O3 (87.7; 87.9) and low amounts of MgO (0.65; 0.8) and TiO2 (0.68; 0.8). The other emits a bright blue luminescence and is low in Al2O3 (78.7; 79.2) and high in MgO (3.3; 3.7) and TiO2 (6.5; 7.9) (in wt. %). The oxide CaO is about the same in both varieties. It is suggested that the change in the color of the visible luminescence results from changes in composition. The origin of hibonite which occurs in complex mineral assemblages together with anorthite, gelhenite, wollastonite, aluminous diopside, andradite, Ca-pyroxene, perovskite, spinel, taenite, chromite, and pentlandite, and in close proximity to nodules containing calcite, whewellite, forsterite and many of the aforementioned phases, is discussed. The proposition that hibonite and associated phases originated by contact metamorphism and metasomatism of calcite-dolomite bearing assemblages cannot, at this time, be completely ruled out.

Keil, K.↗
NASA NTRS1972

Lunar anorthosite 15415 - Texture, mineralogy, and metamorphic history.

Lunar anorthosite 15415 consists almost entirely of anorthite (homogeneous anorthite 96.6 molecule percent), with accessory diopsidic augite and traces of hypersthene, ilmenite, and a silica mineral. The rock has had a complex metamorphic history. The texture reflects at least two episodes of shearing (followed by intense and partial recrystallization, respectively), one episode of cataclastic deformation, and one or more episodes of shattering and fragmentation.

James, O. B.↗
NASA NTRS1972

The moon as a high temperature condensate

The accretion during condensation mechanism is used to explain the differences in composition of the terrestrial planets and the moon. Many of the properties of the moon, including the enrichment in Ca, Al, Ti, U, Th, Ba, Sr and the REE and the depletion in Fe, Rb, K, Na and other volatiles can be understood if the moon represents a high temperature condensate from the solar nebula. Thermodynamic calculations show that Ca, Al and Ti rich compounds condense first in a cooling nebula. The high temperature mineralogy is gehlenite, spinel perovskite, Ca-Al-rich pyroxenes and anorthite. The model is consistent with extensive early melting, shallow melting at 3 A.E. and with presently high speed internal temperatures. It is predicted that the outer 250 km is rich in plagioclase and FeO. The low iron content of the interior in this model raises the interior temperatures estimated from electrical conductivity by some 800 C. The lunar crust is 80 percent gabbroic anorthosite, 20 percent basalt and is about 250-270 km thick. The lunar mantle is probably composed of spinel, merwinite and diopside with a density of 3.4 g/cu cm.

Anderson, D. L.↗
NASA NTRS1972

The Oro Grande, New Mexico, chondrite and its lithic inclusion.

The Oro Grande, New Mexico, U.S.A., chondrite was found in 1971. Electron microprobe analyses and microscopic examination show the following mineralogy: olivine (Fa 19.3 mole %), orthopyroxene (Fs 16.2 mole %), diopside, feldspar (An 13.6 mole %), chlorapatite, whitlockite, kamacite, taenite, troilite, chromite, and an iron-bearing terrestrial weathering product. A bulk chemical analysis of the meteorite shows the following results (weight %): Fe 0.84, Ni 1.46, Co 0.07, FeS 3.62, SiO2 34.18, TiO2 0.14, Al2O3 1.83, Cr2O3 0.55, Fe2O3 21.25, FeO 9.13, MnO 0.31, MgO 21.52, CaO 1.72, Na2O 0.70, K2O 0.08, P2O5 0.25, H2O(+) 2.14, H2O(-) 0.40, C 0.22, sum 100.41. On the basis of composition and texture the Oro Grande meteorite is classified as an H5 chondrite.

Fodor, R. V.↗
NASA NTRS1973

Sample 67955 - A description and a problem

Clasts in breccia sample 67955 contain relatively coarse olivine and plagioclase in part enveloped by poikilitic hypersthene and diopside. This distinctive texture is concluded to result from high temperature crystallization in the presence of a fluid phase, probably a silicate melt. A problem posed by this rock is whether the bulk chemistry, characterized by a high Mg/Fe ratio but low total Fe + Mg, is the result of primary igneous processes on the moon or whether it is the residual end product of a multiple distillation process resulting from repeated meteorite impacts.

Hollister, L. S.↗
NASA NTRS1974

Apollo 17 1-2 mm fines - Mineralogy and petrology

Nine 1-2 mm Apollo 17 soil samples from the South Massif and the Sculptured Hills are examined using petrographic and microprobe techniques. Each soil was separated into six groupings based on macroscopic features observed under a stereomicroscope. The groups and their characteristics are described. Minor differences observed include a higher content of fine-grained, dark, friable breccia and a higher content of high-Mg mafic-bearing fragments in the Sculptured Hills soils. The olivine and pyroxene compositions for light breccia from the soil samples are summarized. During the soil examination, several distinctive fragments seen include coarse orthopyroxene-plagioclase fragments with diopside-rich veins, a plagioclase-forsterite fragment with an igneous texture and a pyroxene-plagioclase fragment with isotropic, subhedral plagioclase grains.

Steele, I. M.↗
NASA NTRS1975

Calcium-aluminum-rich inclusions in the Allende meteorite - Evidence for a liquid origin

We have made a detailed examination of the mineralogy, textures, and assemblages of six calcium-aluminum-rich inclusions (CAI) in the Allende meteorite. They can be classified into four types - hibonite-bearing, fassaite- and olivine-bearing, feldspathoid-bearing and fassaite-bearing CAI that are hibonite and olivine free. Examples of each type appear to have crystallized from a liquid rather than by agglomeration of solid nebular condensates. Some lines of evidence for a liquid origin are the presence of spherical and ovoid shapes and rims containing minerals that are more refractory than minerals inside the inclusion. Thermodynamic calculations and comparisons with liquidus phase diagrams indicate that the CAI could have been produced by direct condensation to metastable subcooled liquids that subsequently crystallized or by remelting of an equilibrium high-temperature condensate by impact. The diopside rims in some hibonite-bearing CAI and the paucity of metal in fassaite-olivine-bearing CAI are more consistent with direct condensation of a liquid.

Blander, M.↗
NASA NTRS1975

Optical constants of minerals and rocks

Lorentz line parameters (and estimates of their standard deviations) have been empirically derived from measured reflectance data for muscovite mica, an anorthosite, a diopsidic pyroxenite, an almandite-pyrope garnet, and a soda lime glass. These parameters provide a useful starting point for computer calculations requiring optical constants as a function and are therefore given here. A novel method of fitting the reflectance data by least squares is described in detail, as is the statistical procedure for estimating the standard deviations of the parameters found.

Aronson, J. R.↗
NASA NTRS1975

High temperature condensates among meteors

It is noted that two meteors which exhibited no lines of iron or sodium in their spectra have been tentatively attributed to aubrites in order to explain their lack of iron. It is shown, however, that no meteorites, including aubrites, have simultaneously low abundances of iron and sodium and that possible parent materials other than aubrites must be considered for the observed meteors. Other possible parent materials considered in this letter include melilite and diopside, two minerals containing both Ca and Mg but neither Fe nor Na. It is suggested that meteoroids rich in Ca and Mg but lacking Fe and Na might form a reservoir for the so-called 'lost' elements (Ca, Mg, Al, Ti, the lanthanides, and other refractory elements) which are depleted in ordinary and enstatite chondrites relative to cosmic abundances.

Wilkening, L. L.↗
NASA NTRS1976

Amoeboid olivine aggregates in the Allende meteorite

Greyish-brown irregularly-shaped aggregates composed predominantly of olivine make up nearly 2% of the Allende meteorite by volume. Many of the aggregates are constructed of subspherical lumps of micron-sized crystals of olivine, pyroxene, nepheline and sodalite surrounded by coarser-grained olivine. Rarely, anorthite, spinel and perovskite are also present. The olivine ranges in composition from Fo64 to Fo99. Pyroxenes range from aluminous diopside to hedenbergite to very Al-rich and Ti-Al-rich varieties. The nepheline contains 1.6-2.4% K2O and 1.6-5.2% CaO but the sodalite is significantly poorer in these elements. The spinel contains 2.1-13.4% FeO. Textural information and oxygen isotopic data suggest that the aggregates are composed of primary, solid condensates from the solar nebula. The perovskite, spinel and Ti-Al-rich pyroxenes are the remains of high-temperature condensates, but the olivine compositions and the presence of feldspathoids indicate that some of the grains continued to react with the solar nebular vapor in the temperature range 500-900 K.

Grossman, L.↗
NASA NTRS1975

The Igwisi Hills extrusive 'kimberlites'

The petrography and mineral chemistry of volcanic rocks from the Igwisi Hills in Tanzania are discussed. There is considerable evidence to suggest that the Igwisi rocks are extrusive kimberlites: a two-component nature with high P-T minerals in a low P-T matrix; the presence of chrome pyrope, Al enstatite, chrome diopside, chromite and olivine; a highly oxidized, volatile-rich matrix with serpentine, calcite, magnetite, perovskite; high Sr, Zr, and Nb contents; occurrence in a narrow isolated vent within a stable shield area. The Igwisi rocks differ from kimberlite in the lack of magnesian ilmenite, the scarcity of matrix phlogopite, and the overall low alkali content. They apparently contain material from phlogopite-bearing garnet peridotites with a primary mineral assemblage indicative of equilibrium at upper mantle temperatures and pressures. This primary assemblage was brought rapidly to the surface in a gas-charged, carbonate-rich fluid. Rapid upward transport, extrusion, and rapid cooling have tended to prevent reaction between inclusions and the carbonate-rich matrix that might otherwise have yielded a more typical kimberlite.

Reid, A. M.↗
NASA NTRS1976

Chromium basalts - Experimental determination of redox states and partitioning among synthetic silicate phases

Experiments were performed on silicate compositions in the forsterite-anorthite-silica and forsterite-anorthite-diopside systems to determine the relative amounts of Cr(II), Cr(III), and Cr(VI) over a wide range of oxygen partial pressures from 10 to the -10th to 1 atm at 1500 and 1550 C. Redox states were measured by visible absorption spectroscopy and electron paramagnetic resonance spectroscopy and titration. It was found that Cr is present almost exclusively as Cr(III) in terrestrial basaltic liquids and as a mixture of Cr(III) and Cr(II) in lunar basaltic liquids.

Schreiber, H. D.↗