  In this paper we have recalled the semiclassical metric obtained from a
classical analysis of the loop quantum black hole (LQBH). We show that the
regular Reissner-Nordstrom-like metric is self-dual in the sense of T-duality:
the form of the metric obtained in Loop quantum Gravity (LQG) is invariant
under the exchange "r <-> a0/r" where "a0" is proportional to the minimum area
in LQG and "r" is the standard Schwarzschild radial coordinate at asymptotic
infinity. Of particular interest, the symmetry imposes that if an observer at
"r" close to infinity sees a black hole of mass "m" an observer in the other
asymptotic infinity beyond the horizon (at "r" close to "0") sees a dual mass
"mp/m" ("mp" is the Planck mass). We then show that small LQBH are stable and
could be a component of dark matter. Ultra-light LQBHs created shortly after
the Big Bang would now have a mass of approximately "10^(-5) mp" and emit
radiation with a typical energy of about 10^(13) - 10^(14) eV but they would
also emit cosmic rays of much higher energies, albeit few of them. If these
small LQBHs form a majority of the dark matter of the Milky Way's Halo, the
production rate of ultra-high-energy-cosmic-rays (UHECR) by these ultra light
black holes would be compatible with the observed rate of the Auger detector.
