The methodology described in paragraph 2.3 was applied to all
the reference materials and to the archeological copals, whether
internal or external samples. Concerning the Raman results, the
decomposition step ended up with altogether 10 Raman bands,
which were present or absent depending on the material. Table 1 is
a summary of the 10 Raman bands, and indicates the materials for
which they are present/absent. The 10 groups of bands were
defined with an arbitrary step of 20 cm−1. Each group is constituted
by the major vibrational contributions of CH bond in different
functional groups, and/or different structural environments. Bands
1,4,and 5 are mainly related to CH2 groups; bands 2,6, and 7 to
CH3 groups and bands 3 and 8 to CH groups in respectively aliphatic
and cyclic groups. Finally, bands 9 and 10 are related to CH or CH2 in
aromatic or vinyl groups. The presence or absence of band sum-
marized in Table 1 is thus already a discriminating criterion
between materials, since it reflects the CH region morphology.