The binary Mn+Sb2O3 pyrotechnic composition was investigated for mining detonator time delay applications. EKVI thermodynamic modelling predicted two maxima in the adiabatic reaction temperature. The local maximum, at a manganese fuel content of ca. 36wt-%, corresponds to a pure thermite-type redox reaction: 3Mn+Sb(2)O(3)3MnO+2Sb. The overall maximum in the adiabatic reaction temperature (ca. 1640K), at the fuel-rich composition of 49wt-% Mn, is consistent with the reaction 5Mn+Sb(2)O(3)3MnO+2MnSb, i.e. a combination of the standard thermite with an additional exothermic intermetallic reaction. XRD analysis of combustion residues confirmed the formation of MnSb and Mn2Sb for fuel-rich compositions. Burn rates were measured using delay elements assembled into commercial detonators. The d(50) particle sizes were 23.4 and 0.92m for the Mn fuel and Sb2O3 oxidant powders, respectively. The delay elements comprised rolled lead tubes with a length of 44mm and an outer diameter of 6.4mm. The rolling action compacted the pyrotechnic compositions to 74 +/- 2% theoretical maximum density. The burning rate increased linearly from 4.2 to 9.4mms(-1) over the composition range 25-50wt-% Mn.