The present invention pertains to glass containing, in terms of mass % on an oxide basis, 40-80% of SiO.sub.2, 1-30% of Al.sub.2O.sub.3, and 1-40% of CaO, the glass having dmisteinbergite as the crystalline phase. Such glass makes it difficult for cracks to progress and has exceptional crack resistance.

Provided is a high-strength crystallized glass or substrate having a high visible light transmittance and a good color balance, which is suitable for use in protecting members of portable electronic devices, optical devices and the like. Provided is a crystallized glass comprising, in terms of mol % on an oxide basis: an SiO.sub.2 component of 30.0% or more and 70.0% or less, an Al.sub.2O.sub.3 component of 8.0% or more and 25.0%, an Na.sub.2O component of 0% or more and 25.0% or less, an MgO component of 0% or more and 25.0% or less, a ZnO component of 0% or more and 30.0% or less and a TiO.sub.2 component of 0% or more and 10.0% or less, the molar ratio [Al.sub.2O.sub.3/(MgO+ZnO)] having a value of 0.5 or more and 2.0 or less, and comprising one or more selected from RAl.sub.2O.sub.4, RTi.sub.2O.sub.5, R.sub.2TiO.sub.4, R.sub.2SiO.sub.4, RAl.sub.2Si.sub.2O.sub.8 and R.sub.2Al.sub.4Si.sub.5O.sub.18 as a crystal phase.