Recently a new phase of solid molecular hydrogen called hydrogen-A was found to occur for pressures greater than 153 GPa (1.53 Mbar) at 77 K. In this paper, from measurements of the dispersion of the refractive index, we find that the frequency of the lowest-energy electronic optical transitions go to zero at 148(19) GPa by extrapolation. This results suggests a dielectric catastrophe and that the hydrogen-A phase is the molecular metallic phase of hydrogen. We argue that the dielectric catastrophe can be associated with closure of the valence-conduction band gap, rather than exciton condensation. Detailed confirmation awaits measurements in the 150 GPa region.