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.     

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 Published and unpublished data on minor and trace elements in the bulk meteorite and in the pyroxene are presented in tabular form.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 COMPOSITION OF THE CHASSIGNY METEORITE

Spark source mass spectrometric analysis of the Chassigny meteorite has given the following data (in ppm): Rb 0.4, Sr 7.2, Y 0.64, Zr 1.5, Nb 0.32, Ba 7.1, La 0.39, Ce 1.12, Pr 0.13, Nd 0.54, Sm 0.11, Eu 0.038, Gd 0.11, Tb 0.02, Dy 0.12, Ho 0.03, Er 0.09, Yb 0.10, Pb 1.0, Th 0.057, U 0.021. These data, in conjunction with major element composition and mineralogical and textural features, indicate that this meteorite is an olivinerich cumulate, possibly genetically related to the nakhlites.     

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     

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.     

PETROGRAPHY AND CHEMISTRY OF THE FAUCETT METEORITE,BUCHANAN COUNTY,MISSOURI

Nine, possibly ten, stones from northwestern Missouri are known as the Faucett meteorite. These stones are finds, but may be fragments of a large fireball seen in the area in 1907. The meteorite is an olivine-bronzite chondrite (H4) containing approximately 31% chondrules and 69% matrix. Modal analysis gives: olivine 43%, orthopyroxene 28.3%, oligoclase 5.9%, glass 1.2%, metallic grains (both nickel-iron and troilite) 19.7%, other minerals and unidentified grains 2.0%. The chemical analysis is typical of modern analyses of H-group chondrites with a total iron value of 26.59 weight percent.     

THE MAGNETIC INVESTIGATION OF THE SIKHOTE-ALIN IRON METEORITE SHOWER AT THE SITE OF FALL

Individual and splinter specimens of the iron meteorite shower of Sikhote-Alin and rock samples from impact craters have been studied magnetically. The results indicate that: 1) Histograms for the distribution of natural remanent magnetization J_n of individual and splinter specimens are characterized by a high correlation coefficient (0.82 ± 0.06). For the splinter specimens, a trend to an increase in number of specimens with anomalously high J_n values is observed; 2) the Earth's magnetic field did not greatly affect the magnetic properties of this iron meteorite; and 3) for rock samples taken from different craters, there was found to be a relation between the natural remanent magnetization and the energy conditions of the crater formation.     

POTENTIOSTATIC STUDY OF IRON METEORITE CORROSION

A potentiostat was used to study the electrolytic corrosion of iron meteorites in a neutral solution. Low current densities were chosen so that the observed potentials would more closely approximate the theoretical Nernst values. Iron, nickel, and cobalt ions, the products of corrosion, were soluble in the electrolyte solution, and were determined after each electrolysis by atomic absorption spectrophotometry. Kamacite and taenite dissolved as individual phases, with kamacite dissolving preferentially. Cobalt dissolved along with iron and nickel from each phase. There is a direct relationship between nickel content and the potential at which a meteorite first starts to dissolve; the higher the nickel content, the more resistant the meteorite is to corrosion. None of the six meteorites observed started to dissolve at a lower potential than pure iron, nor at a higher potential than pure nickel     

MINERALOGY OF THE BOCAIUVA IRON METEORITE: A PRELIMINARY STUDY

The Bocaiuva iron contains 10 to 15% by volume of silicate inclusions which are surrounded by kamacite (6.5 wt % Ni). The metal shows a Widmanstätten pattern in metal areas devoid of silicates; taenite evolved in plessite fields. The silicate inclusions occur as nodules, and as irregular or chain-like aggregates in which olivine may be rounded or faceted. The magnesian silicates (forsterite, enstatite, diopside) are similar in composition to those of the group IAB irons, whereas the interstitial plagioclase is much more calcic (An 50) than that usually found. Iron sulfide occurs as pyrrhotite and contains 1–2 wt% Cu. Chromite and euhedral magnetite are accessory phases always associated with pyrrhotite. Some patches of pyrrhotite enclose rounded chromite and small plagioclase crystals displaying compositions different from those of the ground mass of the inclusions. Schreibersite shows a compositional variability. This preliminary study underlines the unusual nature of Ms iron and raises several questions concerning the genetic relations between silicates, sulfide and metal, and the thermal history of the whole material.     

MORPHOLOGIES OF IRON CRYSTALS FROM THE HAVERÖ METEORITE

Studies of unpolished chips of the Haverö meteorite using the scanning electron microscope (SEM) and the electron microprobe (EMP), show two types of metallic iron particles: A, discrete convex globules of 5 to 50 microns made up of lamellae and interlocked grains, evenly interspersed among the matrix; B, flattened contorted crystals, less than one micron, lining the iron globules and cavities in the silicates or forming rounded spiny bodies. This second type of iron is interpreted, according to the current theory, as resulting from the in situ reduction of iron-magnesium silicates     

PLASMA CHEMISTRY OF METEORITES—I. CLEANSING AND REDUCTION OF THE ODESSA IRON METEORITE

Three small samples of the Odessa, Texas iron meteorite, two surrounded by sandy soil, were introduced into a hydrogen plasma. The soil was effectively cleansed from the iron surfaces, being substantially destroyed with only a fine dust remaining. The appearance of the iron meteorite samples indicated that the terrestrial oxidation was reversed, probably to magnetite, Fe₃O₄, and metallic iron.     

THE VERKHNE DNIEPROVSK IRON METEORITE SPECIMENS IN THE VIENNA COLLECTION AND THE CONFUSION OF VERKHNE DNIEPROVSK WITH AUGUSTINOVKA

It is now a hundred years since a small amount of meteoritic material labelled Verkhne Dnieprovsk was first described. Since then the material has been controversial, due to the corroded character and the very limited amount of material known. Authentic samples, totalling 8 g, have been identified in the Vienna collection, which confirm that Verkhne Dnieprovsk is a unique meteorite, both in its composition, belonging to group II E, and in its heavily shocked and distorted structure. The shock-produced structures include micromelts with a phosphorus gradient, suggesting that the melts originated in situ from mm-sized schreibersite crystals. Unfortunately, no additional information as to location and circumstances of find was discovered at this late date. Further work will probably require field work and interviews on the site and/or studies of Russian archives.     

THE NEEDLES (CALIFORNIA) IRON METEORITE

The Needles fine octahedrite, which weighs 45.3 kg, was found in 1962 in the Turtle Mountains, about 50 km SSW of Needles, California. It contains 10.3% Ni, 77 ppm Ga, 93 ppm Ge and 4.8 ppm Ir, and is a member of chemical group II D. It is rather similar to the Wallapai, Arizona, meteorite, and may possibly be a transported mass from this multiple fall. The compositional evidence slightly favors the interpretation that Needles is a distinct fall.     

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.     

JERSLEV,THE FIRST IRON METEORITE FROM DENMARK

Jerslev is a new iron meteorite of 40 kg, found 1976 on the island of Sjaelland, Denmark. The coordinates are 55°36'N, 11°13'E, and the altitude 20 m. It was excavated from moraine deposits from a depth of about 0.5 m. Jerslev is a coarsest octahedrite of group IIB, related to Mount Joy and Sikhote-Alin. It shows intergranular corrosion from a long exposure to terrestrial groundwater rich in chlorides.     

THE INMAN,McPHERSON COUNTY,KANSAS METEORITE

Inman (find, 1966) is a single, relatively unweathered stone of 7.25 kg that contains fresh metal and only few weathering products away from fractures. It has a pronounced chondritic texture, with 38 vol % of the meteorite being made up of chondrules of virtually all textural types. The recalculated bulk analysis, particularly the ratios of Fe_total/SiO₂ (0.46), Fe°/Fe_total (0.35), and Fe°/Ni° (6.67) and the contents of Fe_total (19.45%) and metallic nickel-iron (7.94%), indicate that Inman is an L-group chondrite. The pronounced chondritic texture; the compositional variabilities of olivine, pyroxene, chromite, and ilmenite; the presence of a fine-grained, nearly opaque matrix, glass and twinned monoclinic low-Ca pyroxene indicate that the chondrite belongs to petrologic type 3.     

NEUTRON DIFFRACTION STUDY OF MUNGINDI IRON NICKEL METEORITE

The Mungindi Iron Nickel Meteorite was investigated by neutron diffraction. All layers of the γ-phase (separated from each other by α-phase bars) form, from the crystallographic point of view, the same, big single crystal. The perfection of this single crystal is very high. In the kamacite phase each individual “single crystal” is broken into a group of crystals.     

THE NORTON COUNTY METEOROID: A CASE FOR STATISTICAL STUDY OF METEORITE FRAGMENTS

The size distribution of 15,000 fragments from the Norton County meteorite was examined with size-frequency histogram. The size is measured in phi units. The estimates of the moments β₁ and β₂ of the empirical distribution were used for approximating the latter with a theoretical frequency curve in terms of the Pearson system It was suggested that the beta distribution obtained from the Pearson system can be regarded as a superposition of two simpler distributions: a near to normal one, corresponding to a slower process of fragmentation, and a power-law one, assumed to result from fast fragmentation process. … All meteorite falls are important but some are more important than others … … This fall was of outstanding importance because with its arrival the entire picture of the word meteorite as portrayed in the total of collections throughout the world was notably altered … H. H. Nininger, 1949. Significance of the Norton, Kansas, meteorite in Transactions of the Kansas Academy of Sciences 52 , 113.