Why ionic crystals are hard and brittle ?

Explanation

(i) Ionic crystalline are hard because they are bound together by strong electrostatic attractive forces.
(ii) To maximize the attractive force, cations are surrounded by as many anions as possible.
(iii) It pressure is applied to ionic crystal, then ionic of similar charge may be forced to get closer to each other.
(iv) The electrostatic repulsion can be enough to split or disorient completely the lattice infrastructure . Thus impairing the belittle charter.