Blue bone analyses as a contribution to the study of bone taphonomy in San Josecito Cave, Nuevo Leon, Mexico

Blue-stained bones, collected along a single stratigraphic level in San Josecito Cave, Nuevo León. México, were analyzed in order to better understand the diagenetic processes that pertained to their formation, and in order to ascertain if those processes could be used in inferring past environmental conditions. Using XRD, two minerals were identified as composing the fossil bone, hydroxylapatite and calcite. INAA, ICPS, XRFS, and colorimetric methods were used to quantify trace elements, including Cu, Sr, Zn, F, and Cl (in descending order). The findings point to the presence of a physical phenomenon produced by transition metal ions impurities, that in turn seems to be associated with physical and chemical processes occurring inside the cave, rather than with outside paleoenvironmental conditions.