The invention relates to a glass ceramic armour material consisting (in % by weight in relation to oxide base) of 5-33 SiO2, 20-50 Al2O3, 5-40 MgO, 0-15 B2O3, 0.1-30 Y2O3, Ln2O3, As2O3, Nb2O3 and/or Sc2O3 and 0-10 P2O5. The inventive armour material can also be reinforced with inorganic reinforcing fibres in a quantity of 5-65% by weight, preferably consisting of C, SiC, Si3N4, Al2O3, ZrO2 or Sialon. Said armour material is characterised in that it exhibits a high elasticity modulus and is producible from green glass without to fear a premature crystallisation.