Results 171 to 180 of about 13,405 (212)
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Amino acids in carbonaceous chondrites
Origins of Life, 1974For almost 20 years laboratory experiments have advanced the concepts of chemical evolution, particularly with regard to formation of the amino acids. What has been generally lacking is concrete natural evidence for this chemical evolution hypothesis.
J G, Lawless, E, Peterson
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The compositional classification of chondrites: III. Ungrouped carbonaceous chondrites
Geochimica et Cosmochimica Acta, 1982Abstract Seven carbonaceous chondrites (Allan Hills A77307, Adelaide, Al Rais, Coolidge, Grosnaja, Karoonda and Renazzo) with uncertain classifications were analyzed by instrumental and radiochemical neutron activation analysis for 29 elements: Na, Mg, Al, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, As, Se, Br, Ru, Cd, Sb, La, Sm, Eu, Yb, Lu, Os ...
Gregory W. Kallemeyn, John T. Wasson
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Meteoritics, 1981
According to its petrography, uniform olivine, Fa23.8, and pyroxene, Fs20.4, a total iron content of 22.9 wt % Fe, 16.4 wt % FeO and an FeO/FeO + MgO ratio of 24.7 mol %, the Tambakwatu is a veined, intermediate hypersthene (Cia) or L6 chondrite.
K. Fredriksson +3 more
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According to its petrography, uniform olivine, Fa23.8, and pyroxene, Fs20.4, a total iron content of 22.9 wt % Fe, 16.4 wt % FeO and an FeO/FeO + MgO ratio of 24.7 mol %, the Tambakwatu is a veined, intermediate hypersthene (Cia) or L6 chondrite.
K. Fredriksson +3 more
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Geochimica et Cosmochimica Acta, 1956
Abstract Chondrites have uniform gallium contents; the average of nineteen samples is 5.3 p.p.m. Ga, with the range 4.2–6.8 p.p.m. Composites of these contain an average of 3.2 p.p.m. Ga in the silicate phase, 15 p.p.m. in the metal phase, and 12 p.p.m. in the sulphide phase.
Hiroshi Onishi, E.B Sandell
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Abstract Chondrites have uniform gallium contents; the average of nineteen samples is 5.3 p.p.m. Ga, with the range 4.2–6.8 p.p.m. Composites of these contain an average of 3.2 p.p.m. Ga in the silicate phase, 15 p.p.m. in the metal phase, and 12 p.p.m. in the sulphide phase.
Hiroshi Onishi, E.B Sandell
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Journal of Geophysical Research, 1967
The Hg abundance has been determined in chondritic meteorites by neutron activation and separation by volatilization over a series of temperatures ranging from 110° to 1200°C. Hg is highly fractionated between classes of chondrites and within the classes themselves.
G. W. Reed, S. Jovanovic
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The Hg abundance has been determined in chondritic meteorites by neutron activation and separation by volatilization over a series of temperatures ranging from 110° to 1200°C. Hg is highly fractionated between classes of chondrites and within the classes themselves.
G. W. Reed, S. Jovanovic
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Geochimica et Cosmochimica Acta, 1962
Abstract The concept of chondrites as metamorphic rocks is examined. Mineralogies of four chondrites whose textures indicate different degrees of thermal recrystallization are presented. It appears that relatively unmetamorphosed or “primary” chondritic material consisted of reduced chondrules (metallic iron, magnesian silicates) in an oxidized ...
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Abstract The concept of chondrites as metamorphic rocks is examined. Mineralogies of four chondrites whose textures indicate different degrees of thermal recrystallization are presented. It appears that relatively unmetamorphosed or “primary” chondritic material consisted of reduced chondrules (metallic iron, magnesian silicates) in an oxidized ...
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Space Science Reviews, 1963
The carbonaceous chondrites are a group of stony meteorites characterized by the presence of an appreciable amount of carbonaceous material other than free carbon (diamond and graphite). They have been divided into three subgroups known respectively as Type I, Type II, and Type III.
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The carbonaceous chondrites are a group of stony meteorites characterized by the presence of an appreciable amount of carbonaceous material other than free carbon (diamond and graphite). They have been divided into three subgroups known respectively as Type I, Type II, and Type III.
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Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences, 1988
A compilation of data on 78 elements in the nine groups of chondrites shows each to be isochemical with the exception of a few volatiles. With the exception of the most volatile elements, the groups have solar abundances to within a factor of two. The solar abundances and the chemical and physical properties of phases in the leastaltered chondrites ...
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A compilation of data on 78 elements in the nine groups of chondrites shows each to be isochemical with the exception of a few volatiles. With the exception of the most volatile elements, the groups have solar abundances to within a factor of two. The solar abundances and the chemical and physical properties of phases in the leastaltered chondrites ...
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Physics Today, 1965
Organic compounds that come from outer space in meteorites are probably relics of a primordial gas phase, conclude Martin Studier (Argonne National Laboratory), Ryoichi Hayatsu, and Edward Anders (both of the University of Chicago). Moreover the gas phase was probably the solar nebula, and during planetary evolution the organics were probably formed ...
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Organic compounds that come from outer space in meteorites are probably relics of a primordial gas phase, conclude Martin Studier (Argonne National Laboratory), Ryoichi Hayatsu, and Edward Anders (both of the University of Chicago). Moreover the gas phase was probably the solar nebula, and during planetary evolution the organics were probably formed ...
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Geochimica et Cosmochimica Acta, 1966
Abstract Fifteen enstatite chondrites have been recognized: Abee, Adhi Kot, Atlanta, Bethune, Blithfield, Daniel's Kuil, Hvittis, Indarch, Jajh deh Kot Lalu, Khairpur, Kota-Kota, Pillistfer, St. Mark's, Saint-Sauveur and Ufana. Their essential minerals are enstatite and/or clinoenstatite (40–60%), kamacite (20–28%), troilite (7–15%), and sometimes ...
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Abstract Fifteen enstatite chondrites have been recognized: Abee, Adhi Kot, Atlanta, Bethune, Blithfield, Daniel's Kuil, Hvittis, Indarch, Jajh deh Kot Lalu, Khairpur, Kota-Kota, Pillistfer, St. Mark's, Saint-Sauveur and Ufana. Their essential minerals are enstatite and/or clinoenstatite (40–60%), kamacite (20–28%), troilite (7–15%), and sometimes ...
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