Charles F. Lewis

Fullerenes from a Fulgurite

Peaks at 720 and 840 atomic mass units were identified by mass spectrometry in a sample extracted from a fulgurite, which is a glassy rock that forms where lightning strikes the ground. The peaks are interpreted as arising from C60 and C70 and the associated peaks as produced from other fullerenes. The intense conditions generated by the lightning not only melted the rock it struck and fused the associated soil but also allowed fullerenes to form, presumably from the organic debris in the soil.

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.

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.

Stishovite at the Cretaceous-Tertiary Boundary, Raton, New Mexico

Stishovite, a dense phase of silica, has become widely accepted as an indicator of terrestrial impact events. Stishovite occurs at several impact structures but has not been found at volcanic sites. Solid-state silicon-29 magic-angle spinning nuclear magnetic resonance (silicon-29 MAS NMR) and X-ray diffraction of samples from the Cretaceous-Tertiary boundary layer at Raton, New Mexico, indicate that stishovite occurs in crystalline mineral grains. Stishovite was indicated by a single, sharp resonance with a chemical shift value of -191.3 ppm, characteristic of silicon in octahedral coordination, that disappeared after heating the sample at 850� Celsius for 30 minutes. An X-ray diffraction pattern of HF residuals from the unheated sample displayed more than 120 peaks, most of which correspond to quartz, zircon, rutile, and anatase. Eight unambiguous weak to moderate reflections could be ascribed to d-spacings characteristic of stishovite.

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.

Total Carbon and Nitrogen Abundances in Lunar Samples

Total carbon and nitrogen abundances were determined by using combustion-gas chromatographic techlniques. Weighited mean analyses for butlk fines were 225 and 140 ppm total carbon and 150 anid 100 ppm total nitrogen. Total carbon in fine breccia was 230 ppm; in coarse breccia, 100 ppmn; in fine-grained rock, 70 ppm; and in mediumn-grained rock, 64 ppm. The finest sieved fraction had the highest carbon content. Total nitrogen in fine breccia was 125 ppm; in coarse breccia, 100 ppm; in fine-grained rock, 115 ppm; and in medium-grained rock, 30 ppm. The total carbon and nitrogen finies appeat to be mixtuires of indigenous lunar material togetheer with meteoritic and solar wind components.

Variations in the chemical and mineralogical composition of rim and plains specimens of the Canon Diablo meteorite.

Abstract Quantitative chemical and modal mineralogical analyses were made on samples representing “rim” and “plains” populations of the Ca on Diablo meteorite. These investigations indicated that the volume per cent of the taenite plus plessite phase, the volume per cent of oxide phase, the total weight per cent nickel and the density are different to a level of significance of 0.05 for each of the populations. Other phases and chemical constituents determined showed no significant differences. The values obtained for the components showing differences were: taenite plus plessite, “rim” 3.98 and “plains” 1.53 vol.%; oxide (lawrencite), “rim”

Carbon content and carbonate 13C abundances in the Early Precambrian Swaziland sediments of South Africa

Abstract Carbon content (0.02–0.68% organic), carbonate content (0–69.7%) and carbonate 13C abundances ( − 7.5−+2.3‰ ) were obtained on samples from the Swaziland sediments of South Africa, which are among the oldest known sedimentary rocks on earth (> 3·109 years old). The carbon chemistry of these sediments may serve as evidence for early life and/or for products of chemical evolution. The variation of organic and carbonate carbon concentrations in different sedimentary horizons seems to be controlled by differences in depositional and diagenetic histories. The carbonate δ 13C values did not vary significantly from the ordinary range of Phanerozoic limestone values.

Thermoluminescence and the origin of the dark matrix of Fayetteville and similar meteorites

Abstract The induced thermoluminescence properties and carbon contents of the dark matrix and light clasts of 6 regolith breccias have been measured. The TL sensitivity of the matrix (normalized to that of the clasts) decreases from ~0.8 to ~0.3 with increasing inert gas content, increasing abundances of highly volatile elements and carbon, and decreasing amounts of interstitial, grain-boundary glass. For meteorites with the highest inert-gas contents (Fayetteville and Leighton), the matrix samples have broader TL peaks (by ~ 10°C) and lower peak temperatures (by ~ 10°C) than the light clasts, whereas meteorites with low inert-gas contents (e.g. Pantar) do not show this difference in the TL properties of the two lithologies. It is argued that the data are consistent with the formation of the dark matrix by comminution of the light clasts with the addition of a component, perhaps CM-like chondrites, with TL properties distinct from those of ordinary chondrites. The present data are inconsistent with the matrix being a new “primitive” material akin to type 3 ordinary chondrites, or with the dark matrix being related to the clasts by purely thermal processes.