COSMIC-RAY AND GAS-RETENTION AGES OF THE CHASSIGNY METEORITE

The sole known chassignite, Chassigny, has a mean radiation age of 8.9±0.5 Myr, rather typical for a stony meteorite. Its low²⁶ Al content (47.8±4.4 dpm/kg) and high ³He/²¹ Ne ratio (5.9) suggest that its preatmospheric size was not much greater than its recovered mass of 4 kg. Its K-Ar age is relatively short, 1.39±0.17 AE, presumably due to a late outgassing event in its parent body     

THE COMPOSITION OF THE JOHNSTOWN METEORITE

A new analysis of the Johnstown meteorite, a hypersthene achondrite, gives the following results (weight percent): SiO₂ 53.48, TiO₂ 0.12, Al₂O₃ 1.43, Cr₂O₃ 0.83, FeO 15.63, MnO 0.54, MgO 25.87, CaO 1.40, Na₂O 0.04, K₂O 0.00, P₂O₅ 0.00, H₂O+ <0.1, H₂O- 0.05, Ni <0.05, Co <0.01, FeS 1.18, sum 100.57. Published and unpublished data on minor and trace elements in the bulk meteorite and in the pyroxene are presented in tabular form.     

THE ISOTOPIC COMPOSITION OF TELLURIUM IN THE ABEE METEORITE

Smith et al. (1978) measured the isotopic composition of tellurium in a number of whole rock meteorites by solid source spectrometry and concluded that all the data were identical to a terrestrial standard within experimental errors. However, Oliver et al. (1981) reexamined the data reported by Smith et al. (1978) and argued that, in the case of the Abee meteorite, a negative anomaly in ¹²⁴Te may be present, supporting the claim for a similar anomaly in Allende. The present work reports two sets of measurements of the tellurium isotopic composition of Abee, and compares the meteoritic data with a terrestrial tellurium standard. No isotopic anomalies can be distinguished within the error limits. However, further work on the isotopic composition of Te in residues from the Allende meteorite need to be pursued by accurate mass spectrometric analysis.     

THE CHEMICAL COMPOSITION AND CLASSIFICATION OF THE KAROONDA METEORITE

New bulk compositional results are presented for the Karoonda meteorite which show that it is a member of the Vigarano type carbonaceous chondrites. Use of the petrographic symbol CK for Karoonda is shown to be unnecessary and inadvisable.     

COMPOSITION AND ORIGIN OF THE UNUSUAL OKTIBBEHA COUNTY IRON METEORITE

We have analyzed Oktibbeha County, the most Ni-rich iron meteorite, for Ni, Co, Cu, Ga, Ge, As, Sb, Ir, and Au. Cu and Sb are higher than in any other iron, but other trace elements are within the ranges typically found in iron meteorites. Extrapolation of trace element trends in group IAB indicates that Oktibbeha County is a member of this group. This sheds light on the origin of groups IAB and IIICD, which are thought to be derived from impact melts on parent bodies of chondritic composition. Lafayette (iron), another sample reported in the literature to have a similarly high Ni content, is probably a pseudometeorite.     

THE CHEMICAL COMPOSITION OF THE HAVERÖ METEORITE AND THE GENESIS OF THE UREILITES

The chemical composition of Haverö is presented and compared with the composition of the other five ureilites     

X-RADIOGRAPHY OF SLABS OF THE ALLENDE METEORITE

X-radiographs of eight slabs of the Allende meteorite, each about 8 mm thick, reveal significant chemical and textural heterogeneities of our Allende fragment at the 100–1000 g level. They also reveal systematic arrangements of chondrules (“strings”). Our preliminary interpretation is that the observed features are probably all due to regolith processes on Allende's parent body, and that these processes included “mini” slope slides along dry, “sandy” slopes.     

THE MINERALOGY AND CHEMISTRY OF THE ALTA'AMEEM METEORITE

The Alta'ameem hypersthene chondrite is a light gray brecciated and metamorphosed meteorite composed mainly of olivine (27% Fa), orthopyroxene (24.5% Fs) and plagioclase (An¹⁰). Other minerals include troilite, kamacite, taenite, chromite, ilmenite, clinopyroxene, chalcopyrite, and apatite or merrillite. The mineralogical and chemical analyses suggest that the Alta'ameem meteorite belongs to the amphoterite group of chondrites. The chemical composition includes the following: Fe 3.39, Ni 1.13, Co 0.05, Cu 0.01, FeS 6.48, SiO₂ 39.48, TiO₂ 0.28, Al₂O₃ 2.25, FeO 16.46, MnO 0.40, MgO 25.66, CaO 1.47, Na₂O 1.05, K₂O 0.15, P₂O₅ 0.47, Cr₂O₃ 0.45; total 99.18.     

THE METEORITE CRATERS OF MORASKO IN POLAND

In 1914, in Morasko near Poznań, a 77.5 kg iron meteorite was found. Later there were additional findings. In 1955 seven crater-like structures, situated in the neighborhood of the meteorite finds, were identified. Until now it has been doubtful whether the iron meteorites and the craters belong together. New examinations by the author confirm beyond any doubt that the meteorites and the craters were caused by the same event.     

THE GUJARGAON METEORITE

The Gujargaon meteorite was observed to fall on a cotton field at Gujargaon in Dewas district, Madhya Pradesh, India, on the afternoon of the 4th of September, 1982. It is an oriented stone with a saucer-shaped front and regmaglypted rear with surfaces of more than one generation, and is entirely covered by fusion crust. Gujargaon is an H5 chondrite with rare chondrules integrated with the matrix. Intense fracturing with fractures filled by glassy veins, and undulose extinction and deformation-twin lamellae in troilite bear evidences of shock. Compared to average H-group chondrites Gujargaon appears to have higher contents of SiO₂and normative pyroxene.     

THE HEDJAZ METEORITE

The Hedjaz meteorite has been studied in detail and on a chemical basis, with 22.1% total Fe, 9% metallic Fe, 1.3% Ni and constant olivine composition (Fa_23–24), can be classified as an L-group chondrite. However, petrographically Hedjaz is quite hoterogeneous and contains features characteristic of types 3, 4, 5, and 6, observations that refute a petrographic type classification. Indeed, Hedjaz, as a complex breccia, exhibits no evidence of metamorphic equilibration after accretion and supports the contention that type 4 (also 5 and 6) chondrites are not derivatives of type 3 material, and that types 5 and 6 are not necessarily more “metamorphosed,” only better crystallized.     

THE LANDES METEORITE

The Landes silicate-bearing octahedrite is a new find from Grant County, West Virginia. Minerals and their compositions are very similar to those in Odessa-type silicate inclusions. The angular nature of the inclusions, recrystallization textures, and mineral compositions indicate a “xenolithic” origin for the inclusions.     

CARBON IN DARK INCLUSIONS OF THE ALLENDE METEORITE

Carbon contents of three Dark Inclusions (DI's) of the Allende meteorite, measured chemically, range from 0.56 to 1.17 weight %. When one includes the data reported by Bunch, Chang, and Ott (two DI's), the lower limit is 0.44%. The C-concentration map of a 1.6 × 1.6 mm² area straddling the boundary of a DI and matrix, or else of a DI and its dark halo, obtained with a ¹²C (d,p)¹³ C nuclear microprobe, shows that the C-content of the core of the DI is very uniform, and that the C-content of the rim is 2.9 ± 0.3 times larger. Variability of C-content of matrix and matrix-like areas of Allende appears to be the rule. DI's cannot be reworked bulk Allende, or precursor for bulk Allende without the addition, respectively removal of significant amounts of carbon. However, some Type 1 DI's might be reworked Allende matrix or precursor matter for that matrix.