  The magnetic phase transition and magnetocaloric properties of mineral and
synthetic melanostibite Mn$_2$FeSbO$_6$ with ilmenite-type structure have been
studied. Mn$_2$FeSbO$_6$ orders ferrimagnetically below 270 K and is found to
undergo a second-order magnetic phase transition. The associated magnetic
entropy change amounts to 1.7 J/kgK for the mineral and 1.8 J/kgK synthetic
melanostibite for 5 T field change. For the synthetic Mn$_2$FeSbO$_6$ the
adiabatic temperature change was estimated from magnetic- and specific heat
measurements and amounts to 0.2 K in 1 T field change. Perspectives of the
promising functional properties of Mn$_2$FeSbO$_6$-based materials are
discussed.
