  We consider the phenomenon of Bose-Einstein condensation of quasi-equilibrium
magnons which leads to a spin superfluidity, the coherent quantum transfer of
magnetization in magnetic materials. These phenomena are beyond the classical
Landau-Lifshitz-Gilbert paradigm. The critical conditions for excited magnon
density for ferro- and antiferromagnets, bulk and thin films are estimated and
discussed. The BEC should occur in the antiferromagnetic hematite at much lower
excited magnon density compared to the ferromagnetic YIG.

Quantum Gases