  The low energy behavior of the $S=1/2$ antiferromagnetic Heisenberg chains
with precious mean quasiperiodic exchange modulation is studied by the density
matrix renormalization group method. Based on the scaling behavior of the
energy gap distribution, it is found that the ground state of this model
belongs to the universality class different from that of the XY chain for which
the precious mean exchange modulation is marginal. This result is consistent
with the recent bosonization analysis of Vidal et al.
