Rocks can only handle so much elastic distortion before permanent deformation, ( failure occurs). but it takes thousands of MPa to break . The theoretical strength of a rock is in the 1000's of MPa but the actual tensile strength is in the 10's of MPa. This came form that the rock was assumed that the atorms were all evenly placed and spaced but there are flaws in the system that impact the elasticity of the object. we couldn't break aperfect bond but thankfully rocks aren't perfect