Study of the structure of mammoth tusk by IR spectroscopy

We studied the structure of the mammoth tusk by infrared spectroscopy, including after heat treatment. The entire complex of functional groups of the tusk components–hydroxyapatite, collagen, and water–was revealed. Collagen is represented in the IR spectrum by the characteristic absorption bands of amide and aliphatic groups. After heat treatment at 600$^\circ$C, the organic part is completely removed from the sample. Hydroxyapatite occurs in the tusk bone tissues in a carbonate-substituted form; the heat treatment at 900$^\circ$C removes the carbonate anion and water from the sample, transiting hydroxyapatite from a nonstoichiometric state to a stoichiometric one.