BRAZIL - PR
Equilibrated Ordinary Chondrite H5.
In the hand sample, the meteorite was collected shortly after its fall and the surface has a thin melting crust that retained most of its black color. Typical regmaglites are clearly evident, but no orientation recorded, which describes their entry, is observable. On its cutting surface, the abundance of metal is apparent and few chondrules can also be seen. Its matrix color is essentially gray with some spots of oxidation. In a thin section, Iguaraçu exhibits varied orifices and partial chondrules that seem to be well integrated into the matrix. The types of chondrules include olivine and porphyritic pyroxene, granular aggregates of subhedral to anhedral olivine and two small barrels of barred olivine. Pyroxene occurs in orthorhombic and monoclinic forms. Lytic fragments dominate the section and the meteorite looks quite fractured. Source: Brooks et al. (1990).
Mineralogically, the most prominent phases present in the thin section are olivine and pyroxene. Electron microscope analyzes of 11 olivines and 10 pyroxenes gave values of Fa18.7 (PMD = 2.26) and Fs16.7 (PMD = 6.23). These values again indicate a group H condrite (Dodd 1981). Some grains of plagioclase and maskelinite were also observed. Metal grains are quite common, with taenite and kamacite being identified. Source: Brooks et al. (1990).
The total chemical abundance is 100.75% for all constituents, including 26.7% (Fe) and 0.57 µg / g (Ir). Based on the critic by Dodd (1981), the Fe content indicates a chondrite of group H. The proportions of atoms, according to Wasson (1974), also indicate a chondrite of group H. Mineralogically, both the composition of olivine and of pyroxene are those expected for a group H condrite. Based on the criteria of Van Schmus & Wood (1967), the petrography of Iguaraçu represents that an H5 condrite is evidenced by the ratio of whole to partial chondrules and by the amount of lithic fragments, despite the partial equilibrium indicated by the silicate data. For more information, the link to access the source is http://adsabs.harvard.edu/full/1990Metic..25..231B. Source: Brooks et al. (1990).
Costa et al. (1988), Sipeira (1989) and Brooks et al. (1990).
A meteorite weighing 1.2 kg was seen to fall on Mr. Sebastião Eufrásio Barbosa's property near Iguaraçu, in the state of Paraná in October 1977. The precise date cannot be determined, because at first the nature of the event was not considered. The mass of approximately 1 kg would have been under the care of the University of Maringá, however apparently nobody seems to know in which department the meteorite would have been. A sample of 82 g is deposited at Massey University, 15.7 g at the British Museum and 15.4 g at the American Museum in New York. Source: Brooks et al. (1990).
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