  Observations by the MACHO collaboration indicate that a significant fraction
of the galactic halo dark matter may be in form of compact objects with masses
$M\sim 0.5M_{\odot}$. Identification of these objects as red or white dwarfs is
problematic due to stringent observational upper limits on such dwarf
populations. Primordial black hole (PBH) formation from pre-existing density
fluctuations is facilitated during the cosmic QCD transition due to a
significant decrease in pressure forces. For generic initial density
perturbation spectra this implies that essentially all PBHs may form with
masses close to the QCD-horizon scale, $M_h^{QCD}\sim 1M_{\odot}$. It is
possible that such QCD PBHs contribute significantly to the closure density
today. I discuss the status of theoretical predictions for the properties of
QCD PBH dark matter. Observational signatures of and constraints on a cosmic
solar mass PBH population are also discussed.
