Comparison of methods for the removal of diagenetic material in buried bone

Three excavated human femurs from the Middle Woodland Gibson site in West Central Illinois and six from the Late Intermediate Estuquiña site in Peru have been subjected to four different cleaning procedures prior to elemental analysis. (A) Simple brushing and washing with distilled water. (B) Physical removal of 1-3 mm of both the outer and the inner surfaces by abrasion. (C) Treatment of powdered bone with 1 N acetic acid. (D) Sequential washing of powdered bone with acetate buffer. Analyses were carried out on subsequently ashed material. Levels of calcium, of organics, and of metallic soil constituents (iron, manganese, aluminium) give an overall indication of contamination and diagenesis. Physical abrasion (method B) is effective in removing bone surface contaminants, particularly iron, manganese, aluminium, potassium and zinc. Chemical procedures permit removal of diagenetic material throughout the bone but also remove some biogenic elements that are present on the surface of the bone crystals. Effects of biogenic constituents were tested by analysing rat pelvic bones that had been subjected to the same four procedures. A combination of physical abrasion and mild chemical washings may provide the best procedure for preparation of bone prior to analysis.