  It is proposed to search for free quarks near their production thresholds. If
the current-quark masses for u, d quarks are smaller than the pion mass,
$u\bar{u}$ and $d\bar{d}$ pairs produced below the pion pair threshold, would
not have sufficient energy to hadronize and could be observable. In the case of
large u,d quark masses and also for the heavy quarks, production near threshold
may show hadronization probability $<1$, and lead to free quarks. Searches for
fractional charges in stable matter could be more promising, through
irradiation of samples at energies near the quark pair production thresholds.
