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Science 10 November 1989:
Vol. 246. no. 4931, pp. 790 - 792
DOI: 10.1126/science.246.4931.790
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Articles

Phyllosilicate Absorption Features in Main-Belt and Outer-Belt Asteroid Reflectance Spectra

Faith Vilas 1 and Michael J. Gaffey 2

1 National Aeronautics and Space Administration Johnson Space Center, Space Science Branch, Houston, TX 77058
2 Geology Department, Rensselaer Polytechnic Institute, Troy, NY 12181

Absorption features having depths up to 5% are identified in high-quality, high-resolution reflectance spectra of 16 dark asteroids in the main belt and in the Cybele and Hilda groups. Analogs among the CM2 carbonaceous chondrite meteorites exist for some of these asteroids, suggesting that these absorptions are due to iron oxides in phyllosilicates formed on the asteroidal surfaces by aqueous alteration processes. Spectra of ten additional asteroids, located beyond the outer edge of the main belt, show no discernible absorption features, suggesting that aqueous alteration did not always operate at these heliocentric distances.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Evidence of Thermal Metamorphism on the C, G, B, and F Asteroids.
T. Hiroi, T. Hiroi, C. M. Pieters, M. E. Zolensky, and M. E. Lipschutz (1993)
Science 261, 1016-1018
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Science. ISSN 0036-8075 (print), 1095-9203 (online)