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Marilia meteorite, Marília, São Paulo, Brazil

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Latitude & Longitude (WGS84): 22° 15' 0'' South , 49° 55' 60'' West
Latitude & Longitude (decimal): -22.25, -49.9333333333
 
Ordinary chondrite (H4;S3)
Fall, 5 October 1971; 2.5 kg,

A late afternoon shower of meteorites led to the recovery of at least 7 stones (780 g and smaller) within the city limits of Marilia. The largest specimen was roughly pyramidal in shape and covered with a uniform dark crust. Within the meteorite distinct chondrules of various types are present embedded in a fine-grained, microcrystalline matrix. Compositionally, bulk iron contents (Fe ~27 wt%) plus olivine (Fa~19) and low Ca-orthopyroxene (Fs~17) compositions are characteristic of the H-chondrite (relatively high in total iron) geochemical group. Mineralogically the meteorite consists primarily of dominant olivine and accompanying orthopyroxene along with minor troilite and Fe-Ni metal. Small amounts of plagioclase, diopside, and chromite are also reported. Plagioclase is found as very small (>20 µm) interstitial grains with only traces of maskelynite present. The presence of distinct chondrules, nearly equilibrated silicates, and two low-Ca pyroxenes (orthopyroxene and often twinned clinopyroxene in a roughly 2:1 ratio) are consistent with the petrologic type 4 classification. Level S3 Shock indicators include planar fractures in olivine as well as shock veins.

A cosmic ray exposure (CRE) age of ~8.11 Ma has been reported for Marilia. Nearly half of all measured CRE ages of H chondrites lie in the 6-10 Ma range — suggests that a major component of today's H chondrite flux may be products of one or two relatively recent catastrophic impacts. The H chondrites are the second largest group of observed meteorite falls (nearly 40% of the fully classified falls. Marilia itself is one of 62 meteorite falls classified exactly as an H4 chondrite [as of May 2016]. The largest total mass (780 g) has been held at the Institute of Geoscience in Salvador while the largest individual fragment (200 g) has been held at the Institute of Mineralogy in Modena, according to the Catalogue of Meteoritics (5/e).

Mineral List



8 entries listed. 4 valid minerals.

The above list contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.

References

Avanzo, P.E., Levi-Donati, G.R. & Sighinolfi, G.P. (1973) The Marilia Meteorite Shower - A Preliminary Report: Meteoritics 8(2), 141-147. (June 1973).

Clarke Jr, R.S. (1974). The Meteoritical Bulletin, No. 52. Meteoritics 9 (1): 101-124. (March 1974).

Gomes, C.B. & Keil, K. (1980) Brazilian Stony Meteorites: University of New Mexico Press: Albuquerque. pp. 162.

Graham, A. L., Bevan, A. W. R. & Hutchison, B. (1985) Catalogue of Meteorites (4/e). University of Arizona Press: Tucson.

Graf, T. & Marti, K. (1995) Collisional History of H Chondrites: Journal of Geophysical Research 100 (E10): 247-263. (Oct 1995).

Grady, M.M (2000). Catalogue of Meteorites (5/e). Cambridge University Press: Cambridge; New York; Oakleigh; Madrid; Cape Town. 689 pages.

Dunn, T.L., Cressy, G., McSween Jr, H.Y. & McCoy, T.J. (2010) Analysis of ordinary chondrites using powder X-ray diffraction: 1. Modal mineral abundances. MAPS 45(1):123-134. (Jan 2010).

Scott, E.R.D., Krot, T.V., Goldstein, J.I., Wakita, S. (2014). Thermal and Impact History of the H Chondrite Parent Asteroid during Metamorphism: Constraints from Metallic Fe-Ni. Geochimica et Cosmochimica Acta. 136 (1): 13-37. (Jan 2014).

Grady, M.M., Pratesi, G. & Moggi-Cecchi, V. (2015) Atlas of Meteorites. Cambridge University Press: Cambridge, United Kingdom. 373 pages.

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