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Lewis, C. F.

Publications and source records attributed to Lewis, C. F..

15 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Systematic chemical variations in large 3AB iron meteorites: Clues to core crystallization

Analysis of numerous individual iron meteorites have shown that fractional crystallization of iron cores result in variations in chemical concentration of the solid core which span several orders of magnitude. The magnitude and direction of the resulting spatial gradients in the core can provide clues to the physical nature of the core crystallization process. We have analyzed suites of samples from three large 3AB irons (Cape York, 58t; Chupaderos, 24t; Morito, 10t) in order to estimate local chemical gradients. Initial results for the concentrations of Ge, Pd, Pt (Massey group), Ir, Au, As, Co, Os, and Rh (Dalhouse group), and P (Arizona group) show significant ranges among the Cape York and Chupaderos samples and marginally significant ranges among the Morito samples. Measurements of Au, Ir, Co, Ni, Cu, Ga, As, W, Re (from UCLA) and Ni and Co (Arizona group) are in progress. We find a spatial Ir gradient in Chupaderos with a magnitude similar to the one reported for Agpalilik (Cape York iron) by Esbensen et al.

Haack, H.↗
NASA NTRS1985

Sulfur in achondritic meteorites

The sulfur abundances of samples of nearly 50 achondrites were examined to enlarge the database on the sulfur contents of various categories of achondrites. The study covered eucrites, howardites, diogenites, shergottites, chassignites, nakhilites, aubrites and three unique specimens. The study was spurred by the possibility that the S abundances could help identify the meteorites as originating on Mars or Venus. The S abundances and distributions varied widely, but confirmed that the data were valid indicators of the brecciation and thermal metamorphic history of each meteorite.

Gibson, E. K.↗
NASA NTRS1973

Total carbon contents of Apollo 15 and 16 lunar samples

The total carbon contents in Apollo 15 fines range from 29 to 170 micrograms/g. Fines from Apollo 16 range from 65 to 280 micrograms/g. These samples are similar to those from Apollo 11, 12, and 14, with dark colored fines generally containing more carbon than lighter fines. Sample 61221 (light colored fines) is anomalously high with 100 micrograms/g total carbon. Correlations between total carbon content and sample collection station for each mission are evident. Basalts from Apollo 15 have less than 27 micrograms/g total carbon. Anorthositic rocks from Apollo 15 and 16 have less than 20 micrograms/g total carbon. Breccias show complex and variable carbon distributions.

Moore, C. B.↗
NASA NTRS1972

The Seoni chondrite.

Description of the Seoni (India, 1966) chondrite in terms of its mineralogy, bulk chemistry, and sample shape and mass. It is an H6 group ordinary chondrite that contains olivine, orthopyroxene, clinopyroxene, plagioclase, together with chromite, troilite, kamacite, taenite, chlorapatite, and whitlockite. Recrystallization has been quite extensive, as indicated by the presence of a few remnant chondrules, low abundance of clinopyroxene, and relatively high abundance of well formed plagioclase.

Bunch, T. E.↗
NASA NTRS1971

Chemical analyses of thirty-eight iron meteorites.

The contents of nickel, cobalt, phosphorus, and carbon are tabulated for 38 iron meteorites. The samples used in the analyses are splits taken from larger samples made by milling chips from the surface of each meteorite. Individual splits from these larger samples give excellent analytical reproducibility. Previously developed criteria (Moore, Lewis, and Nava, 1969) are used to evaluate the quality of old analyses. The results of the old analyses are also tabulated.

Lewis, C. F.↗
NASA NTRS1969

Superior analyses of iron meteorites.

Iron meteorites analysis for Ni, Co, P, C, S and Cu elements by milling technique, noting superiority degree based on Co-Ni correlation

Lewis, C. F.↗