São José do Rio Preto meteorite, São José do Rio Preto, São Paulo, Brazil

Ordinary chondrite (H4)
Fall, 14 August 1962; 927 g, one stone

A single witness observed the morning fall of a single meteoritic stone. Abundant and distinct chondrules of various types are present within a matrix of fine-grained microcrystalline material in the last stages of devitrification. Compositionally, bulk iron contents (Fe ~27 wt%) and olivine (Fa~19) and low Ca-pyroxene (Fs~17) are characteristic of the H-chondrite geochemical group [relatively high in total iron]. Mineralogically the meteorite consists primarily of olivine, Ca-poor pyroxenes, and Fe-Ni metal. Minor phases include albitic plagioclase, diopside, troilite, and chromite. Fe-Ni metal phases include kamacite, taenite, and tetrataenite. Distinct chondrules, nearly equilibrated olivine and pyroxene, the microcrystalline matrix, and presence of twinned low-Ca clinopyroxene ('clinobronzite') combined suggest the petrologic type 'H4' classification.

A cosmic ray exposure (CRE) age of ~8.9 Ma has been recorded. About half of all H chondrites have CRE ages in the 5-10 Ma range — suggesting to some that this subset of H chondrites were involve in one or two relatively recent impacts which now account for approximately half of the H-chondrite meteorite flux.

The H chondrites are the second largest group of ordinary chondrite falls and represent nearly 40% of the witnessed and fully classified falls with the H4 subgroup account for slightly more than 15% of the group. São Jose do Rio Preto is one of the smaller of 51 meteorite falls classified exactly as H5 chondrites (in June 2016).

Mineral List

11 entries listed. 5 valid minerals.

References

External Links