  In this paper we compare the observable properties of 962 numbered MBAs (Main
Belt Asteroids) of Tholen/SMASSII C and S class, with diameter in the range
1-500 km, not belonging to families or binary systems. Above 20 km, the
diameters distributions of C and S are similar while under 20 km there is a
clear observative bias in favour of small S asteroids which prevents a direct
comparison. There is a significant correlation between rotation frequency and
diameter both for C and S: if the diameter decreases the rotation frequency
tends to increase. There is also a significant correlation between the
lightcurve amplitude and the diameter for both samples: if the diameter
decreases the lightcurve amplitude tends to increase. For larger diameter the C
amplitude tends to be systematically higher than S amplitude of about 0.1
magnitude, but the difference is not very significant. Between 48 and 200 km,
the C asteroids have a rotation frequency distribution compatible with a
Maxwellian. On the other side, for S asteroids, the compatibility with the
Maxwellian concernes diameters greater than 33 km. Considering the rotational
properties and the lightcurve amplitude it appears that there are no
substantial differences between the samples of C and S asteroids taken into
account, and this indicates a good homogeneity in the processes of collisional
evolution.
