Figure 3.

Raman spectrum of three minerals unambiguously identified by their Raman bands. Representative Raman spectrum of graphite (D 1308 cm^-1and G 1572 cm^-1); anastase (An), with bands at 637, 512, 394, 196 and 145 cm^-1and calcite (Cc), 1086, 712, 281 and 157 cm^-1recorded at 785 nm laser wavelength. The broad band around 1400 cm^-1could not be unambiguously assigned.