The two commercial animal black pigments, characterized by portable X-ray diffraction, are mainly constituted of hydroxyapatite with impurities of quartz.
The IR spectra from the commercial pigments show also a sharp band at 2013 [cm.sup.-1] not present in the hydroxyapatite spectrum (Figure 7(b) and insert) and diagnostic for the identification and distinction of the animal black pigments [13, 14].
To conclude, the sharp band at 2013 [cm.sup.-1], diagnostic for the animal black pigments, is associated with cyanamidapatite, a degradation product of the synthesis of the black pigment.