Color origin and heat evidence of paleontological bones: Case study of blue and grey bones from San Josecito Cave, Mexico - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue The American Mineralogist Année : 2009

Color origin and heat evidence of paleontological bones: Case study of blue and grey bones from San Josecito Cave, Mexico

Résumé

Results on the investigation of paleontological blue and gray bone fragments of small vertebrates coming from two stratigraphic layers 770 and 720, respectively, at San Josecito Cave (Nuevo Leon, Mexico, dating between 28,000 and 19,000 years BP), are presented. Structural and elemental analyses combining X-Ray Diffraction (XRD), Fourier Transform InfraRed spectroscopy (FT-IR), Transmission Electron Microscopy (TEM) and Particle Induced X-ray and γ-ray Emission (micro-PIXE/PIGE) as well as spectroscopic investigation using UV/visible/near-IR reflectance spectroscopy and X-ray Absorption Near-Edge Structure (XANES) were performed in order to identify precisely the origin of the blue stain. XANES also allowed insights into the origin of the gray stain. Prior research has showed that Mn with the valence state of 5+ in a tetrahedral environment could be responsible for the turquoise blue color in mastodon ivory some tens of million years old that was modified by a heat process. New spectroscopic data evidenced a heat induced modification, revealed traces of Mn among the typical bone constituents (Ca, P, Sr, Zn) and provided insights into the color origin of the blue paleontological bones from San Josecito Cave dating between 44,000 to about 19,000 yr BP. Mananese(V) ions in a tetrahedral environment of four O2- ions in the apatite structure could be evidenced in these bones, the same color origin as in the blue mastodon ivory studied before. Manganese is present in another oxidation state (IV) in gray bones from the same locality. The formation of Mn(V) is induced by heat treatment of the bones under oxidizing conditions. The heating of the bones was confirmed by the direct observation of apatite crystals using TEM. The question, however, is how the heat originated inside the cave.
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Dates et versions

halsde-00450876 , version 1 (27-01-2010)

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  • HAL Id : halsde-00450876 , version 1

Citer

Céline Chadefaux, Colette Vignaud, Emilie Chalmin, Jasinto Robles-Camacho, Joaquin Arroyo-Cabrales, et al.. Color origin and heat evidence of paleontological bones: Case study of blue and grey bones from San Josecito Cave, Mexico. The American Mineralogist, 2009, 94 (1), pp.27-33. ⟨halsde-00450876⟩
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