Archaeological bone ashing

Archaeological bone samples were treated for diagenesis before sample analysis. The bone samples were first mechanically cleaned with the Patterson NC-350 dental drill equipped with a carbide burr to remove any organic matter or contaminants. The mechanical cleaning also removed the layers of cortical bone most susceptible to diagenetic contamination, as well as all traces of trabecular bone. The bone samples were then chemically cleaned in an ultrasonic bath. The samples were first sonicated in water for 30 minutes, then rinsed and sonicated in 5% acetic acid for 30 minutes, and finally rinsed and sonicated with 5% acetic acid for 5 minutes (30, 53, 55, J9).The bone samples were dried for 1 hour at approximately 80°C. Finally, the bone samples were placed in a crucible and ashed at approximately 800°C for 10 hours. 

In an earlier paper (13), the INAA procedure was described and compared to the chemical analysis of bone by using inductively coupled plasma emission spectroscopy (ICPES). The ICPES technique required dissolution of the ashed sample before analysis, but otherwise the techniques proved to be quite comparable. In this study, some of the samples were analyzed by using X-ray fluorescence (XRF) to determine whether there was adequate sensitivity for the study of contamination in archaeological bone. 

All tooth and bone samples were initially prepared in the Laboratory for Archaeological Chemistry by the first author. Modem faunal samples for strontium isotope analysis were placed in a crucible and ashed at approximately 800°C for 10 hours. The bone samples were then crushed in an agate mortar and pestle. The teeth were removed from modem fauna mandibles after ashing and crushed and stored separately from the bone. 

The range of raw materials that humans use for food, construction, valuables, transportation, and other purposes is enormous. Many materials are found at archaeological sites. The Black Earth site in southern Illinois, a settlement of hunters dating from 4000 to 3000 bc provides an example. It is an enormous site, more than a city block in size, and the cultural layer is up to 1.5 m (5 ft) deep. The concentration of ash, excrement, and other organic matter in the sediments changed the chemistry of the soil, resulting in more alkaline conditions, favorable for the preservation of bone and other materials. 

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