Plaga’s ‘scenario 3’, distinct from Giddings-Mangano’s scenario 1 (canonical thermodynamic treatment, decay in ~10^-27 s) and scenario 2 (Hawking radiation switched off ad hoc). The microcanonical treatment (Casadio, Harms, Leblanc) fixes total energy, avoids the unitarity/energy-conservation problems of the canonical picture, and is based on peer-reviewed models; the mBH is a new type of elementary particle (‘quantum black hole’). The normalisation mass M_N lies between the mass whose 5D Schwarzschild radius equals L (eq. 3) and the mass M_C ~ 3Lc^2/G whose radius is ~6L (eq. 5); with the latter normalisation mBHs are quasistable for all allowed L.