What is the relationship between ionic bonds and cleavage?

a) ionic bonds are very strong, so ionic bonded rocks do not have cleavage

b) ionic bonds are weak, so ionic bonded minerals always break into irregular pieces

c) ionic bonds are weak, so predictable cleavage occurs where ionic bonds break easily

d) ionic bonds are strong, so the mineral only shows cleavage where there isn't an ionic bond

The correct answer is d) ionic bonds are strong, so the mineral only shows cleavage where there isn't an ionic bond.

When a crystal of an ionic compound is struck is struck with a sharp edge, the lattice can split along certain plains. As the ions line up in repeating patterns, they form crystals with flat faces and regular angles. The orderly arrangement of ions means that, if the crystal is struck at certain angles, the blow displaces the ions slightly so that the ions of the same charge are momentarily lined up opposite each other. Thy then repeal each other and the crystal is cleaved.