Absorption bands near 3 (m in diffuse reflectance spectra of carbonaceous chondrites: Comparison with asteroids

We measured infrared diffuse reflectance spectra of several carbonaceous chondrites in order to obtain additional information on the surface materials of their presumed parent bodies, C-type asteroids. The presence and intensity of absorption bands near 3 (m in the reflectance spectra are due to the presence and abundance of hydrates and/or hydroxyl ions. The absorption features of the 3 (m hydration bands of carbonaceous chondrites were compared with those of asteroid, 1 Ceres and 2 Pallas. They are commonly classified into separate subtypes, G- and B-type. The spectral shapes of Pallas and Renazzo (CR2 chondrite) around the 3 (m absorption band are an excellent match. This result may suggest that the amount of hydrous minerals in the surface material of Pallas is smaller than that in the CM2 or CI chondrites and the hydrous minerals on the surface of Pallas may be similar to those found in Renazzo. The spectral features around the 3 (m band of Ceres are different from those of carbonaceous chondrites studied in this paper.