Engineering topics

Taylor, L. A.

Publications and source records attributed to Taylor, L. A..

84 records · Page 5

NASA NTRS1974

Formational history of lunar rocks - Applications of experimental geochemistry of the opaque minerals

Experimental data on the cooling histories of lunar rocks are presented along with a descriptive mineralogy of certain opaque minerals in Apollo 17 samples. Lunar rocks having Zr partitionings of coexisting ilmenite and ulvospinel indicative of high-temperature equilibrium (above 1000 C) appear to have cooled rapidly to temperatures below 800-900 C. The Ti content of troilite coexisting with ilmenite can be used to differentiate rock fragments which are mineralogically and texturally similar. It is found that Cr and Mg partitionings between coexisting armalcolite and ilmenite vary notably between rocks so that they can be used to distinguish otherwise similar samples. The spinels are analyzed as varieties of chromian ulvospinel and titanian chromite.

Taylor, L. A.↗

NASA NTRS1974

Beta-FeOOH, akaganeite, in lunar rocks

Experiments were conducted to determine the nature of the alteration process in lunar rocks. Mixtures of 10 wt.% Fe + 10 wt.% FeCl2 + 80 wt.% basalt (terrestrial) were pelletized and allowed to set for 48 hrs at 25 C, at 40% and at 100% relative humidity. The end products were examined by reflected-light microscopy and by X-ray diffraction. The degree of reaction appears to depend upon the amount of FeCl2, the availability of water and the Ni content of the metallic Fe. The experiments showed the extremely rapid rate at which the oxyhydration can occur in air and that the product is beta-FeOOH. The data from the FeOOH mineral in rock 66095 were compared with those obtained from synthetic beta-FeOOH and found to be identical. The 'rust' in the Apollo 16 rocks could result from oxyhydration of the samples, caused by water vapor contamination, all or part of which occurred in the Apollo spacecraft and/or upon return to earth. The akageneite (beta-FeOOH) in lunar rocks could be entirely of terrestrial origin as originally suggested by Taylor et al. (1973).

Taylor, L. A.↗

NASA NTRS1973

Selected Apollo 17 soils - Mineralogy and geochemistry of opaque and non-opaque phases

Soil samples 74220 ('orange soil'), 74241 and 75081 were sized, and the compositions of the opaque and silicate phases were determined. The ilmenites, particularly in 74241, contain up to 7.8 wt % MgO and display higher bireflectance than low-Mg ilmenites. They commonly contain exsolution-like chromite and rutile and occasionally are in association with native Fe in an assemblage probably resulting from reduction. The chromian ulvospinels are similar to Apollo 11 spinels in that they contain near-equal amounts of chromite and ulvospinel molecules. No primary chromites were observed. Most native Fe has No and Co contents of less than 1 wt %; some in 74220 contained 5-6% Ni and less than 1% Co in association with schreibersite.

Taylor, L. A.↗

NASA NTRS1973

Zr partitioning and kinetics and mechanism

The results of investigations concerning the cooling histories of lunar rocks are reported. Publications resulting from this research are listed. Studies discussed include the partitioning of Zr between FeTi03 and Fe2Ti04 in the presence of Fe + Zr02, and ulvospinel reduction.

Taylor, L. A.↗

NASA NTRS1973

The kinetics of ulvoespinel reduction - Synthetic study and applications to lunar rocks.

The kinetics of Fe2TiO4 reduction to FeTiO3 + Fe were studied using CO-CO2 gas mixtures with fO2 measured by a solid ceramic (calcia-zirconia) oxygen electrolyte cell. Isothermal rate studies at 900 C suggest that the mechanism of Fe2TiO4 reduction is one of nucleation and growth, where the growth stage may be controlled by the diffusion of the reactant through the product layer or volume diffusion. The activation energy for the growth stage of the process was determined to be 46 plus or minus 4 kcal/mole.

Mccallister, R. H.↗

NASA NTRS1973

Cooling histories of lunar rocks based on opaque mineral geothermometers

The application of experimentally derived data on (1) the Zr partitioning between coexisting ilmenite and ulvospinel and (2) the Ti partitioning between coexisting troilite and ilmenite has allowed the discernment of differences in subsolidus cooling histories of lunar rocks - e.g., the Apollo 15 Type I Mare basalts. The rocks which show Zr partitionings reequilibrated to lower temperature (i.e., below 950 C), as a result of slow cooling, also show evidence for subsolidus reduction of ulvospinel to ilmenite + native Fe. It is suggested that the presence of ulvospinel reduction is not evidence a priori that these rocks have undergone more reducing conditions than the other Apollo 15 Mare basalts; it may only indicate that the cooling rates were slower in that subsolidus temperature range (i.e., much less than 900 C) where oxygen fugacity values were favorable for ulvospinel reduction. The rocks with higher temperature Zr partitionings and no ulvospinel reduction may have cooled under the same fugacity conditions but at a faster rate.

Taylor, L. A.↗

NASA NTRS1973

Rust in the Apollo 16 rocks

Apollo 16 samples of all four rock types and from all stations contain evidence for hydration and oxidation - i.e., the presence of hydrated iron oxide, probably goethite. Rock 66095 contains native FeNi grains with a characteristic intergrowth of schreibersite and, to lesser extents, of cohenite. Troilite also contains sphalerite. The goethite contains 1.5-4.6 wt.% chlorine and occurs mainly on the edges of FeNi metal, causing a rust color in the cracks and space around the native metal grains, which also contain abundant chlorine. This observation suggests the presence of lawrencite (FeCl2), a phase that deliquesces and oxidizes very rapidly upon exposure to water or to a moist atmosphere.

Taylor, L. A.↗

NASA NTRS1972