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We present a detailed analysis of the prompt and afterglow emission of GRB050410 and GRB 050412 detected by Swift for which no optical counterpart wasobserved. The 15-150 keV energy distribution of the GRB 050410 prompt emissionshows a peak energy at 53 keV. The XRT light curve of this GRB decays as apower law with a slope of alpha=1.06+/-0.04. The spectrum is well reproduced byan absorbed power law with a spectral index Gamma_x=2.4+/-0.4 and a low energyabsorption N_H=4(+3;-2)x10^21 cm^(-2) which is higher than the Galactic value.The 15-150 keV prompt emission in GRB 050412 is modelled with a hard(Gamma=0.7+/-0.2) power law. The XRT light curve follows a broken power lawwith the first slope alpha_1=0.7+/-0.4, the break time T_break=254(-41;+79) sand the second slope alpha_2=2.8(-0.8;+0.5). The spectrum is fitted by a powerlaw with spectral index Gamma_x=1.3+/-0.2 which is absorbed at low energies bythe Galactic column. The GRB 050410 afterglow reveals the expectedcharacteristics of the third component of the canonical Swift light curve.Conversely, a complex phenomenology was detected in the GRB 050412 because ofthe presence of the very early break. The light curve in this case can beinterpreted as being the last peak of the prompt emission. The two burstspresent tight upper limits for the optical emission, however, neither of themcan be clearly classified as dark. For GRB 050410, the suppression of theoptical afterglow could be attributed to a low density interstellar mediumsurrounding the burst. For GRB 050412, the evaluation of the darkness is moredifficult due to the ambiguity in the extrapolation of the X-ray afterglowlight curve.

GRB 050410 and GRB 050412: are they really dark GRBs?