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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

A re-examination of relationships among pyroxene-plagioclase achondrites.

In light of the new data of Jerome (1970), a brief discussion of genetic relationships between eucrites, howardites and diogenites is presented. Howardites are not direct products of magmatic crystallization, as has sometimes been postulated, but instead are interpreted as polymict breccias resulting from the mechanical mixture of eucrites and diogenites. Testing of this model by means of chemical arguments is made complicated however by the probable presence of a chondritic component in howardites and by a sequence analogous to terrestrial differentiation series, among the eucrites themselves.

Jerome, D. Y.↗
NASA NTRS1972

Pyroxenes from breccia 14303.

Review of the investigation results obtained on the adjacent polished thin sections 47 and 53 of breccia 14303, the largest rock returned by Apollo 14 for which a location has not been established. A basaltic lithic clast, composed mainly of plagioclase, olivine, and pigeonite zoned to subcalcic augite, is found to occupy the same relative position in both sections and is assumed to represent a single lithic chip. Further study of lithic and fragmental clasts in breccias is seen likely to yield information on lunar history between 4.6 and 3.9 b.y. ago.

Weigand, P. W.↗
NASA NTRS1974

Low orthopyroxene from a lunar deep crustal rock - A new pyroxene polymorph of space group P21ca

Bronzite crystals (En86Fs11Wo3) from a slowly-cooled lunar troctolitic granulite, have space group P21ca, a postulated, but previously unreported space group. Diffractions violating the b-glide extinction conditions have been observed in long-exposure X-ray precession photographs from three of these crystals and on an automated X-ray diffractometer. P21ca is a subgroup of the common orthopyroxene space group Pbca, and its cell dimensions (a = 18.235 plus or minus 0.004 A, b = 8.831 plus or minus 0.002 A, c = 5.189 plus or minus 0.001 A) are similar to those of terrestrial bronzites. It is postulated that the lower symmetry space group has developed as a result of very slow cooling at pressures of one to two kilobars deep in the lunar crust.

Smyth, J. R.↗
NASA NTRS1978

The Yamato-74659 ureilite and some new findings on the Yamato achondritic pyroxenes

A cube-like fragment with an approximately 4 mm edge was taken from the Yamato-74659 meteorite for the mineralogical and crystallographic examination discussed in the present paper. An analysis of powdered fragments by a standard wet chemical method showed that it matched to weathered ureilite. The chemical composition was found to differ from other ureilites in that the FeO content (8.83 wt%) is the lowest among known ureilites and it is richer in SiO2 contents (42.91 wt%).

Takeda, H.↗
NASA NTRS1979

The pyroxene chemistry of four mesosiderites

The four mesosiderites studied in the present paper have samples similar to pyroxenitic and noritic rocks, but two of them (Morristown and Dyarrl Island) lack the very magnesian orthopyroxenes found in Estherville and Lowicz. Pigeonite crystallized at minimum temperatures of 1170 C in Estherville source rocks (before plagioclase crystallization), 1150 C in Lowicz and Morristown, and 1120 C in Dyarrl Island (after plagioclase crystallization).

Hewins, R. H.↗