There is no appreciable deformation, and crack propagation is very fast. In most brittle materials, crack propagation (by bond breaking) is along specific crystallographic planes (cleavage planes). This type of fracture is transgranular (through grains) producing grainy texture (orfaceted texture) when cleavage direction changes from grain to grain. In some materials, fracture is intergranular.
Fracture occurs due to stress concentration at flaws, like surface scratches, voids,
