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At least 991 records · Page 55
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Rock 14068 - An unusual lunar breccia.

Rock 14068 is a walnut-sized clast of dark breccia from station C1 near Cone Crater. The rock's dominant component is an olivine-rich groundmass. Petrographic and chemical studies were made of polished sections of the rock. The origin of the material is discussed. It is thought possible that the melt was produced by remelting a preexisting lunar rock of the same composition. Another possibility considered is that the rock composition constitutes a mixture of several rock types of partly meteoritic origin.

Helz, R. T.↗
NASA NTRS1972

Structure of lunar glasses by Raman and soft X-ray spectroscopy.

X-ray spectra and Raman spectra have been measured from individual particles of lunar glasses. Each particle was analyzed separately by electron microprobe. Silicon emission shifts vary between parent rock types and can be interpreted as a range of Si-O distances from 1.612 to 1.637 A. Aluminum emission shifts relate to the amount of 4- and 6-coordinated Al in the glass. Raman spectra show broadened bands. Certain bands recur in many specimens and relate to the main normative minerals for the glass bulk composition, olivine, pyroxene, and anorthite.

Fabel, G. W.↗
NASA NTRS1972

The Washougal meteorite.

Optical study of the Washougal (Wash.), howardite, and determination of the ranges of composition of plagioclase and pyroxenes from measurements of densities and indices of refraction. Notable among many unique xenoliths are a round object whose morphology is that of an armored chondrule; a stratified fragment; and a centimeter-sized dunite xenolith (olivine Fa sub 12.8). The abundances of 27 elements, including all major elements and 15 trace elements are reported. To a first approximation, the composition of Washougal corresponds to a mixture of 51 wt per cent of eucritic material and 49 per cent of a diogenitic component, but excesses of some elements suggest a minor component of chondritic composition.

Jerome, D. Y.↗
NASA NTRS1972

The Seminole, Gaines Co., Texas, meteorite.

Description of the external form, composition, and structure of the Seminole meteorite found near Seminole Texas in 1961. Two fragments weighing 41.1 kg were recovered. Analyses show these to be the fragments of a single black olivine-bronzite, or H4-group chondrite, exhibiting brecciation and a moderate number of individual chondrules.

Huss, G. I.↗
NASA NTRS1972

Niobian rutile in an Apollo 14 KREEP fragment.

Niobian rutile was found in a KREEP lithic fragment of basaltic texture. The niobian rutile contains 85.3% TiO2, 7.1% Nb2O5, 2.65% Cr2O3, 0.70% ZrO2, 0.61% SiO2, 0.82% Al2O3 0.61% FeO, 0.52% CaO, 0.22% V2O3 in addition to minor amounts of MnO, MgO, and CeO2. Rare-earth elements were not detected, in contrast with lunar niobian rutile of Marvin (1971). Coexisting minerals in the KREEP fragment are major amounts of plagioclase and orthopyroxene, and minor amounts of olivine, ilmenite, augite, barian K-feldspar, whitlockite, troilite, Ni-Fe, zirkelite, and chromite.

Hlava, P. F.↗
NASA NTRS1972

The Oro Grande, New Mexico, chondrite and its lithic inclusion.

The Oro Grande, New Mexico, U.S.A., chondrite was found in 1971. Electron microprobe analyses and microscopic examination show the following mineralogy: olivine (Fa 19.3 mole %), orthopyroxene (Fs 16.2 mole %), diopside, feldspar (An 13.6 mole %), chlorapatite, whitlockite, kamacite, taenite, troilite, chromite, and an iron-bearing terrestrial weathering product. A bulk chemical analysis of the meteorite shows the following results (weight %): Fe 0.84, Ni 1.46, Co 0.07, FeS 3.62, SiO2 34.18, TiO2 0.14, Al2O3 1.83, Cr2O3 0.55, Fe2O3 21.25, FeO 9.13, MnO 0.31, MgO 21.52, CaO 1.72, Na2O 0.70, K2O 0.08, P2O5 0.25, H2O(+) 2.14, H2O(-) 0.40, C 0.22, sum 100.41. On the basis of composition and texture the Oro Grande meteorite is classified as an H5 chondrite.

Fodor, R. V.↗
NASA NTRS1972

The Haveroe ureilite - Petrographic notes.

Review of the mineralogy and texture of the Haveroe and of some of the six other known ureilites, and assessment of the implications of their observed characteristics. In common with other ureilites, Haveroe shows mineralogical and textural evidence of preterrestrial shock. The olivines and metal grains have been recrystallized, the fabric includes angular voids, and graphite-rich areas are present that have been partially converted to diamonds with some indication of lonsdaleite. On the basis of such features, a subdivision of ureilites into particular types is proposed.

Marvin, U. B.↗
NASA NTRS1973

Luna 20 - Mineralogy and petrology of fragments less than 125-micron size.

Two milligrams of less than 125-micron size particles from the Luna 20 soil sample (22001,17) have been examined. The results of the mineral identification and analysis verify earlier assumptions that the nature of the lunar highlands is predominantly anorthositic in composition. The presence of highly magnesian clinopyroxene, orthopyroxene, and olivine suggests crystallization of highland rocks in an ultrabasic environment. No fragments were observed that could be unequivocally assigned to mare basalt types.

Meyer, H. O. A.↗
NASA NTRS1973

Luna 20 soil - Abundance and composition of phases in the 45-125 micron fraction.

Glass compositions in the Luna 20 soil indicate a minor contribution of mare rocks and a major contribution of highly feldspathic highland material. Glasses with the composition of highland basalt (anorthositic gabbro or norite) predominate in a range of highly aluminous glasses. The analyses of minerals in the soil show that the highland rocks have a unique assemblage of minerals that can readily be distinguished from the mineral assemblages of either mare or KREEP basalts. The soils are characterized by abundant anorthitic, low-Fe plagioclase. Highly magnesian orthopyroxenes, pigeonites, and augites are the most prominent pyroxenes. Unlike mare basalt pyroxenes, clinopyroxenes with intermediate Ca values are not abundant, but extreme iron enrichment toward pyroxferroite does occur. Olivines are more abundant than at other sites and are Mg-rich, low in Ca and Cr. Spinels with compositions approaching MgAl2O4 predominate over pleonastes and chromites. Ilmenite and metal are present but not abundant. The mineral compositions are consistent with derivation from a suite of highly feldspathic rocks in which highland basalt compositions predominate.

Reid, A. M.↗
NASA NTRS1973

Petrology of some lithic fragments from Luna 20.

Microscopic and electron microprobe studies were made of polished thin sections of part of a 30-mg sample of 250- to 500-micron lunar soil returned by Luna 20 from a point between Mare Fecunditatis and Mare Crisium. Very fine-grained lithic (crystalline) rock fragments, composing about one-fifth of the total sample, have mineralogical compositions equivalent to various types of gabbro, anorthositic gabbro, gabbroic anorthosite, and troctolite, with minor basalt. The textures now observed in these fragments are in large part metamorphic. Twenty-seven electron microprobe analyses of minerals from these fragments are presented, including olivine, plagioclase, pyroxene, spinel, nickel-iron, and a Zr-Ti-REE mineral possibly similar to 'phase B' of Lovering and Wark (1971). Analyses of seven melt inclusions and 28 defocused beam analyses of lithic fragments are also given. Some of the fragments contain 'gas' inclusions which, along with the fine grain size, are believed to indicate final crystallization under low pressure near surface conditions.

Roedder, E.↗
NASA NTRS1973

Minor and trace elements in some meteoritic minerals.

Despite the information available (Mason, 1971) on trace elements in different types of meteorites, relatively little is known about the distribution of these elements among the individual mineral phases. The mineral phases including olivine, orthopyroxene, clinipyroxene, troilite, nickel-iron, plagioclase, chromite, and the phosphates were separated from several meteorites. The purified minerals were analyzed for trace and minor elements by spark source mass spectrometry and instrumental neutron activation analysis. The elements are classified as siderophile, lithophile, and chalcophile.

Allen, R. O., Jr.↗
NASA NTRS1973

Uranium and thorium in achondrites.

The abundances of U and Th in 19 achondrites and two pallasite olivines have been measured by radiochemical neutron activation analysis. Brecciated eucrites are enriched relative to chondrites in both elements by factors between 10 and 20, perhaps as a result of a magmatic differentiation process. Two unbrecciated eucrites are far less enriched, possibly due to their origin as igneous cumulates. The diogenites Johnstown and Shalka contain approximately chondritic levels of U and Th, but Ellemeet is 10 times lower. The abundances in three howardites are in good agreement with those expected from major element data for a mixing model with eucrite and diogenite end members. The high O-18 basaltic achondrites Nakhla, Shergotty and Angra dos Reis have a range of U and Th abundances similar to the brecciated eucrites and howardites, but have systematically higher Th/U ratios.

Morgan, J. W.↗
NASA NTRS1973

Characteristics of tracks of ions of 14 less than or equal to Z less than or equal to 36 in common rock silicates.

Identification of heavy ion tracks in minerals by measurements of track etch rates and total etchable track lengths were irradiated with beams of Si, Cl, Ti, Fe, Zn, and Kr at energies up to 10.35 MeV/nucleon. Nine minerals commonly used to study fossil cosmic ray tracks in meteorites and lunar samples. From measurements of etched track length as a function of residual range, response curves for various minerals were determined as a function of ionization rate, using the expression previously derived by Price et al. (1968). These curves increase smoothly with ionization rate instead of rising abruptly at some critical value as was previously thought. It is shown that the track etch rate concept accounts qualitatively for total etchable track length distributions, but that the positions of the peaks of different elements in these histograms occur at shorter lengths for fossil tracks than for fresh tracks. Annealing data indicate that, at maximum lunar surface temperatures, tracks in olivine, orthopyroxenes, and feldspars may be significantly shortened, whereas tracks in clinopyroxenes will not be affected.

Price, P. B.↗
NASA NTRS1973

Photometric and polarimetric properties of the Bruderheim chondritic meteorite.

Study of the spectral, photometric, and polarimetric properties of the Bruderheim olivine-hypersthene chondritic meteorite. This meteorite is representative of the most common meteoritic material recovered on earth, and, hence, could also be the most common in interplanetary space. Yet, comparison with astronomical data indicates that none of the asteroids in the main belt for which adequate observations exist can be matched with Bruderheim properties. Only the surface of the Apollo asteroid Icarus does, in light of polarization and photometry data, appear to be consistent with an ordinary chondrite composition. This suggests the possibility that this material, although common in earth-crossing orbits, is rare as a surface constituent in the main asteroid belt.

Egan, W. G.↗
NASA NTRS1973

Preliminary data on boulders at station 6, Apollo 17 landing site

A cluster of boulders at Station 6 (Apollo 17 landing site) consists of breccias derived from the North Massif. Three preliminary lithologic units were established, on the basis of photogeologic interpretations; all lithologies identified photogeologically were sampled. Breccia clasts and matrices studied petrographically and chemically fall into two groups by modal mineralogy: (1) low-K Fra Mauro or high basalt composition, consisting of 50-60% modal feldspar, approximately 45% orthopyroxene and 1-7% Fe-Ti oxide; (2) clasts consisting of highland basalt composition, consisting of 70% feldspar, 30% orthopyroxene and olivine and a trace of Fe-Ti oxide.

Heiken, G. H.↗
NASA NTRS1972

Apollo 15 rake sample microbreccias and non-mare rocks: Bulk rock, mineral and glass electron microprobe analyses

Quantitative electron microprobe data of Apollo 15 nonmare rake samples are presented. Bulk analyses of lithic fragments in the nomare rocks (expressed in oxide weight-percent) and the corresponding CIPW molecular norms are given. The mineralogy of the rocks and lithic fragments are also given; structural formulae for complete analyses and molecular end-members for all mineral analyses are included. The mineral analyses include pyroxene, olivine, plagioclase, barian K-feldspar, spinel and ilmenite, cobaltian metallic nickel-iron as well as SiO2-K2O-rich residual glass. Electron micropobe analyses (oxide weight percent) of glasses in loose fines and microbreccia samples and their CIPW molecular norms are presented along with electron microprobe data on bulk, mineral, and matrix glass from chondrules.

Hlava, P. F.↗
NASA NTRS1974

Lunar electrical conductivity, permeability,and temperature from Apollo magnetometer experiments

Magnetometers were deployed at four Apollo sites on the moon to measure remanent and induced lunar magnetic fields. Measurements from this network of instruments were used to calculate the electrical conductivity, temperature, magnetic permeability, and iron abundance of the lunar interior. Global lunar fields due to eddy currents, induced in the lunar interior by magnetic transients, were analyzed to calculate and electrical conductivity profile for the moon, and those profiles were used to calculate the lunar temperature for an assumed lunar material of olivine. Simultaneous measurements by magnetometers on the lunar surface and in orbit around the moon were use to construct a whole-moon hysteresis curve, from which the global lunar magnetic permeability is determined. Total iron abundance (sum of iron in the ferromagnetic and paramagnetic states) was calculated for two assumed compositional models of the lunar interior. Other lunar models with an iron core and with a shallow iron-rich layer also discussed in light of the measured global lunar permeability. Simultaneous magnetic field and solar plasma pressure measurements show that the remanent fields at the Apollo 12 and 16 sites interact with, and are compressed by, the solar wind. Velocities and thicknesses of the earth's magnetopause and bow shock were also estimated from simultaneous magnetometer measurements.

Dyal, P.↗
NASA NTRS1974

Mauna Kea

Mauna Kea, the highest of Hawaii's five volcanoes, is the only high landmass in the central Pacific Ocean basin to bear unmistakable signs of Pleistocene glaciation. The stratigraphic record indicates that a summit ice cap formed and disappeared at least four times in the last 250,000 years, and that volcanic eruptions characterized not only the interglacial intervals, but also two of the glacial periods as well. Exposed rock units on the upper slopes of Mauna Kea have been divided into two major groups based on gross lithologic character. The Hamakua Group comprises the bulk of the subaerial shield of the volcano and consists largely of thin-bedded pahoehoe flows of olivine basalt. The overlying Laupahoehoe Group consists of a thin cap of alkalic lavas and pyroclastic layers confined largely to the upper slopes of the mountain. Interstratified with the volcanic units are sedimentary formations that provide evidence of four episodes of ice cap glaciation.

Porter, S. C.↗