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Ibitira meteorite, Ibitira, Martinho Campos, Minas Gerais, Brazil

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Latitude & Longitude (WGS84): 20° South , 45° West
Latitude & Longitude (decimal): -20, -45


Fell June 30, 1957; 2.5 kg
Eucrite, monomict

Ibitira is an unbrecciated basaltic meteorite composed primarily (>90 vol%) of a 2:1 mix of pyroxene (pigeonite with exsolved augite) and anorthitic plagioclase. Tridymite constitutes ~4-5 vol% and there are a number of opaques. Unlike most meteorites the metallic iron in Ibitira is Ni poor (Ni<1%). For the last three decades Ibitira has been recognized as an oddball among those pyroxene-plagioclase meteorites classified as 'eucrites.' For one, unlike normal Eucrites with Na-rich, albitic plagioclase, Ibitira's plagioclase is Ca-dominated anorthite. And, Ibitira is one of the very few meteorites known which has open vugs with once free-growing crystals inside. (Apparent "vugs" in other meteorites are just atmospheric ablation holes, and contain no free-standing crystals.)

Ibitira's textural and chemical peculiarities compared to other eucrites have been further underscored by recent developments. In particular, studies of Ibitira's differing oxygen isotope ratios and Fe/Mn ratios have made it seem highly unlikely that Ibitira is derived from the same parent body as other eucrites. To be sure, most planetary scientists believe that most of the HED clan (howardites, eucrites, diogenites) are fragments of the asteroid Vesta. But Ibitira and Pasamonte are just two of several Eucrite 'look-a-likes' which appear to have been derived from other some other ancient and differentiated asteroids. [Quite conceivably these other asteroids have been destroyed or shattered beyond recognition over the past 4 eons.]

Note: The included Mittlefehldt and more recent references are provided for the reader who wants to 'get beyond' the strictly mineralogical story which, of course, is quite interesting in itself.

Mineral List


12 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

Wilkening, L. L. & Anders, E. (1975) Some studies of an unusual eucrite: Ibitira. Geochimica et Cosmochimica Acta 39: 1205-1210.

Steele, I. M. & Smith, J. V. (1976) Mineralogy of the Ibitira eucrite and comparison with other eucrites and lunar samples: Earth and Planetary Science Letters 33: 67-78.

Mason B., Jarosewich E. & Nelen J. A. (1979) The pyroxene-plagioclase achondrites. Smithson. Contrib. Earth Sci. 22: 27-45.


D. W. Mittlefehldt, T. J. McCoy, C. A. Goodrich, & A. Kracher (1998). Non-chondritic meteorites from asteroidal bodies. In: Planetary Materials (Papike, J. J., Editor): Chapter 4, 195 pages. Mineralogical Society of America: Washington, DC, USA. (1998)

Heim, N. A., Wadhwa, M. & Davis, A. M. (March 1999) Rare Earth Element Abundances in Vapor Deposited Minerals in Ibitira Vesicles: Lunar and Planetary Science Conference XXX: abstract no. 1908. (March 1999)

Davis, A. M., Dufek, J. D., & Wadhwa, M. (2001) Euhedral Phosphate Grains in Vugs and Vesicles in Ordinary Chondrites, Lunar Samples and the Ibitira Eucrite: Implications for Trace Element Transport Processes. Meteoritics & Planetary Science 36(Supplement): p. A47 (Sept 2001)


David W. Mittlefehldt (2005) Ibitira: A basaltic achondrite from a distinct parent asteroid and implications for the Dawn mission. MAPS 40 (5): 665-677. (May 2005)

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