CAMEL DONGA METEORITE,A NEW EUCRITE FROM THE NULLARBOR PLAIN,WESTERN AUSTRALIA

Twelve stones, ranging up to 504 g (total weight 2.92 kg), of a very fresh eucrite have been collected from a 1 km² area on the Nullarbor Plain in Western Australia. The location is approximately 75 km N6°E from Nurina Siding on the Trans-Australian Railway; coordinates 30°19′S, 126°37′E. This eucrite consists almost entirely of pyroxene (mean composition Wo 16 Fs 49) and plagioclase (mean composition An 85) in approximate proportions 3: 2, with 2% almost pure Fe metal and accessory amounts of troilite, ilmenite, and an SiO₂ phase. Gabbroic and doleritic clasts are present in a groundmass of comminuted pyroxene and plagioclase. The chemical composition (weight per cent) is: SiO₂ 49.53, TiO₂ 0.74, Al₂O₃ 12.49, Cr₂O₃ 0.33, FeO 16.07, MnO 0.56, MgO 6.31, CaO 10.41, Na₂O 0.49, K₂O 0.04, P₂O₅ < 0.01, H₂O + < 0.1, H₂O — 0.07, Fe metal 2.07, Ni < 0.01, Co < 0.01, FeS 0.19, C 0.03, sum 99.33.     

TWO NEW IRON METEORITES FROM WESTERN AUSTRALIA

Two new iron meteorites from Western Australia are described: Cosmo Newberry — a 2.156 kg meteorite of unusual spiky shape, and Gnowangerup — a 33.6 kg pear-shaped meteorite. X-ray fluorescence spectrometry shows that Cosmo Newberry can be classified in Group IIA, whilst Gnowangerup is a member of Group IIIAB. Neither iron can be associated with any other Western Australian meteorite.     

THE GOSNELLS IRON — A FRAGMENT OF THE MOUNT DOOLING OCTAHEDRITE

A 1.5 kg iron found in 1960 at Gosnells, near Perth, Western Australia, belongs to Wasson's chemical group I-An3 and is structurally unusual, being best described as a heat-altered granular coarse octahedrite. It is chemically and structurally very similar to the Mount Dooling iron, found in 1909 about 400 km away, and has a fracture surface which fits the Mount Dooling mass very closely. The Gosnells fragment was probably transported by human agency, though it is not known when or by whom.     

RICA AVENTURA: A NEW IRON METEORITE FROM CHILE

Rica Aventura, a group IVA fine octahedrite, was found in 1910 near the now abandoned village of Rica Aventura, Chile (69° 37′W, 21° 59′S). Based on chemical evidence it appears to be a unique new find.     

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.     

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     

FOUR NEW IRON METEORITE FINDS

Four new irons are described; Buenaventura (IIIB) from Chihuahua, Mexico: mass 114 kg; Denver City (anomalous) from Texas, USA: mass 26.1 kg; Kinsella (IIIB) from Alberta, Canada: mass 3.7 kg; and Tacoma (IA) from Washington, USA: mass 17 g. Denver City is unique, i.e., not related to any other known iron. Tacoma is the smallest iron meteorite recorded. All were purchased for the UCLA collection following a publicity drive for new meteorites     

THE TOULON METEORITE: A NEW CHONDRITE FROM ILLINOIS

Toulon is an olivine-bronzite chondrite found near Toulon, Illinois in 1962. It contains abundant, well preserved chondrules, as well as glasses that are not well devitrified. Most of the metal has been weathered out. Olivine and pyroxene are well equilibrated. We have classified it as an H5 chondrite.     

NEW SPECIMENS FROM THE FAUCETT,MISSOURI, METEORITE LOCALITY

In December, 1966, Brookins and Twiss reported the finding of two specimens of an olivine-bronzite chondrite near Faucett, Missouri. Since that date, six additional specimens have been found. Another probable specimen was found but later lost. This paper describes the circumstances of all nine finds and presents a map of the discovery sites.     

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.     

HAMMOND DOWNS,A NEW CHONDRITE FROM THE TENHAM AREA,QUEENSLAND, AUSTRALIA

Among a collection of meteorites from the area of the Tenham shower (Queensland, Australia) was a 27 kg stone which proved to be different from the other Tenham stones. It is a bronzite, H4, chondrite, the principal minerals being olivine (average composition Fa _18.8), clinobronzite and bronzite (average composition Fs_16.4), nickel-iron, and troilite; it is considerably weathered, much of the nickel-iron being converted to limonite. It has a highly chondritic structure, with devitrified glass within the chondrules, and without visible plagioclase. This meteorite was found about 1950 near the Hammond Downs station, hence the name; its coordinates are lat 25° 28′ S., long 142° 48′ E.     

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.     

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 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 RUHOBOBO,RWANDA METEORITE: A NEW L6 CHONDRITE

Ruhobobo is a new meteorite which fell in Rwanda, Africa, in 1976. We found and analyzed olivine (Fa 23.4), opx (Fs 19.7, Wo 1.4), cpx (Fs 7.5, Wo 44.0), plagioclase (An 11.7, Or 5.6), chromite, “whitlockite”, kamacite, taenite and troilite. Based on these analyses and on microscopic observation, Ruhobobo is an unshocked L6 chondrite.     

THE NARAGH METEORITE: A NEW OLIVINE-BRONZITE CHONDRITE FALL

At 9:20 A.M. on August 18, 1974, a stony meteorite of approximately 3200 grams struck the roof of a secondary school at Naragh, Central Iran, (51°30′E, 33°45′N). The ellipsoidal dark-gray meteorite was 17 × 15 × 13 cm (density 3.62 gr/cm³). XRF and wet chemical analysis yields the bulk composition of the meteorite as follows in weight percent: Fe 11.95, Ni 1.05, Co 0.07, FeS 5.49, SiO₂ 37.15, TiO₂ 0.15, Al₂O₃ 2.43, Cr₂O₃0.62, FeO 14.25, MnO 0.23, MgO 23.79, CaO 1.61, Na₂O 0.92, K₂O 0.08, P₂O₅ 0.26. Modal mineral contents (in volume percent) are olivine 40, orthopyroxene 25, clinopyroxene 3, plagioclase 10.5, chromite 0.80, phosphate 0.70, troilite 6, metal phases 14. The meteorite is fine-grained, with average grain size about 0.4–0.6 mm and contains numerous recrystallized glassy chondrules. Olivine occurs as laths and radiating crystals in chondrules and as coarse-grained phenocrysts and interstitial microcrystalline grains in the matrix. These olivines have relatively uniform composition (Fo_80–82Fa_20–18). Fine-grained skeletal orthopyroxenes of average composition (En₁₆Fs₈₂Wo₀₁) are inter-grown with olivine in both chondrules and matrix. Clinopyroxene and plagioclase of average composition (En_6.5Fs₄₈Wo_45.5) and (Ab₈₂An₁₂Or₀₆) respectively, are evenly distributed in the matrix, together with kamacite (Fe_92–95), plessite (Fe_69.6–82.2) and taenite (Fe_46.7–66.1), troilite (Ni-free) and chromite grains. The high ratios of total Fe to SiO₂ of 0.71, metallic Fe to total Fe of 0.54, and SiO₂ to MgO of 1.56 in the bulk composition, the Fa component of olivine grains of 17.5–19.6, and the high Ca content of orthopyroxenes between 0.53 and 0.87 wt % suggest that the Naragh meteorite belongs to the H-group and petrologic type 6 of Van Schmus and Wood (1967) classification. In addition, the occurrence of fine-grained clear sodic plagioclase, the presence of numerous recrystallized chondrules with homogeneous silicate minerals, and the absence of Ni in the sulfide phase indicate that the Naragh meteorite has been metamorphosed after the initial crystallization in the parental body.