MICRO BLACK HOLES are hypothetical tiny black holes, for which quantum mechanics effects play an important role. It is possible that such quantum primordial black holes were created in the high-density environment of the early Universe (or big bang), or possibly through subsequent phase transitions. They might be observed by astrophysicists in the near future, through the particles they are expected to emit by Hawking radiation.  (Wikipedia 15 Mar 2012)

"Quantum" = the minimum amount of any physical entity involved in an interaction.

A quantum blackhole, a micro blackhole, is the least substantial form of blackhole it is possible to have and consists of three adjacent and gravitationally bound gravitons. Such a blackhole is surrounded by a gravitysheath interface within which its gravitypull is greater than that of any other object. It is at the gravitysheath interface that its vergence velocity is related to its escape velocity and thus its stability condition determined. A micro blackhole can be overstable with its vergence velocity being less than its escape velocity, stable with its vergence velocity being the same as its escape velocity, or understable with its vergence velocity being more than its escape velocity.