Carleton B. Moore

Adsorption of arsenite and arsenate on amorphous iron hydroxide

Adsorption isotherms in solutions with ionic strengths of 0.01 at 25°C were measured over the arsenite and arsenate concentration range 10−7−10−3 M and the pH range 4–10. At low concentrations, these isotherms obeyed equations of the Langmuir type. At higher concentrations the adsorption isotherms were linear, indicating the existence of more than one type of surface site on the amorphous iron hydroxide adsorbent. Removal of arsenite and arsenate by amorphous iron hydroxide throughout the concentration range were determined as a function of pH. By careful selection of the relative concentration of arsenic and amorphous iron hydroxide and pH, removals on the order of 92% can be achieved.

Amino acid analyses of the Murchison, Murray, and Allende carbonaceous chondrites

Three carbonaceous chondrites were examined for water-extractable amino acids. The Murchison Murray specimens were found to be of similar amino acid composition. This similarity suggests that these amino acids in are indigenous to type II carbonaceous chondrites. The Allende (type III) carbonaceous chondrite was found to be essentially devoid of amino acids on the basis of on identical analysis.

Amino acids indigenous to the murray meteorite.

Analysis of the Murray meteorite, a type II carbonaceous chondrite, has led to the identification of 17 amino acids. For seven of the amino acids nearly equal amounts of the D and L isomers are present, and 11 of the amino acids are not found in protein. These results suggest that these amino acids, like the amino acids of the Murchison meteorite, are extraterrestrial in origin.

Total nitrogen and carbon abundances in carbonaceous chondrites

Abstract Total nitrogen and carbon abundances in twenty-seven samples of nineteen carbonaceous chondrites have been measured. The results obtained indicate that the meteorites enriched in nitrogen are similarly enriched in carbon. The results support the previously observed trends with the highest carbon and nitrogen concentrations in Type I (C-1) carbonaceous chondrites with decreasing amounts in Type II and Type III (C-2, C-3, C-4) carbonaceous chondrites. The Vigarano and Ornans subgroups of the C-3 chondrites have differences in their carbon and nitrogen contents.

Superior Analyses of Iron Meteorites

New analyses have been made on 100 iron meteorites for the elements nickel, cobalt, phosphorus, carbon, sulfur, and copper. The meteorites were sampled using a new milling technique which provided chipped samples. Replicate analyses of high analytical precision were made on splits from these samples. On the basis of these new analyses graphical methods were used for the evaluation of earlier analyses of iron meteorites. The abundances of phosphorus, carbon and sulfur show variations depending upon the concentrations of non-metallic mineral phases taken in the sampling procedure. Cobalt and nickel show a positive correlation with each other. On the basis of this relationship approximately 35% of analyses done before 1907, as reported by Farrington, may be classified as ‘superior’ and suitable for use in calculations today. More recent analyses show a higher degree of superiority. Within selected gallium-germanium groups direct relationships between cobalt, nickel and phosphorus may also be predicted.

Amino Acids in an Antarctic Carbonaceous Chondrite

Amino acids have been found in aqueous extracts of a C2 carbonaceous chondrite recovered from Antarctica. The composition of the amino acids strongly suggests that they have a meteoritic origin. Comparison of these results with those obtained with other C2 chondrites supports the view that Antarctic meteorites have not been significantly altered by terrestrial processes since their fall.

Lithium, sodium and potassium abundances in carbonaceous chondrites

Abstract Concentrations of lithium, sodium, and potassium in 18 carbonaceous chondrites were determined in the same sample solution by atomic absorption. Mean abundances in carbonaceous Type I chondrites are, in atoms 10 6 Si: Li = 60.1, Na = 5800, K = 3700. Relative to Type I carbonaceous chondrites, abundances in Type IIs are: Li = 0.87, Na = 0.61, K = 0.58; and in Type IIIs Li = 0.82, Na = 0.49, K = 0.36. Evidently there is a differential depletion of potassium relative to sodium in Type IIIs, suggesting a fractionation after accretion.

Carbon Abundances in Chondritic Meteorites.

Combustion analyses of total carbon in chondritic meteorites indicate a fractionation of this element between the various types of chondrites. The median values for the percentage of carbon by weight are 0.40 for enstatite chondrites, 0.09 for olivine-bronzite chondrites, and 0.08 for olivine-hypersthene chondrites. Olivine-pigeonite chondrites show great variations in their carbon contents.

The chemical composition of metallic spheroids and metallic particles within impactite from Barringer Meteorite Crater, Arizona

Abstract Atomic absorption analyses of 25 metallic spheroids from Barringer Meteorite Crater have been carried out for Fe, Ni, Co and Cu. In addition, electron microprobe analyses of 58 impactite metallic particles have been carried out for Fe, Ni and Co from four different impactite samples. The normalized Ni, Co and Cu contents of the spheroids were from 13–22 per cent, 0.8–1.3 per cent and 260–430 μg/g, respectively. These figures represent enrichment factors of 2–3 in the spheroids compared to analyses of the bulk meteorite. The Co/Ni and Cu/Ni ratios in the spheroids are close to the respective ratios in the bulk meteorite. This suggests that the spheroids were formed by preferential removal of iron by oxidation from a chemically homogeneous liquid. The impactite metallic particles had Ni contents from 10 to 95 per cent and Co contents from 0·3 to 4 per cent. The Co contents of these particles showed a positive correlation with Ni up to 60 per cent Ni and a negative correlation beyond 60 per cent Ni. Reaction of the impactite metallic particles with SiO 2 of the target can explain these variations. Our findings show that extensive chemical reaction between projectile and target occurs at impact.

The distribution of total carbon content in enstatite chondrites

Abstract Total carbon abundances in thirteen enstatite chondrites range from 0.056 wt% in Khairpur to 0.56 wt% in Kota Kota. The enstatite chondrites cannot be subdivided into two groups on the basis of their carbon contents.