The kind of solid that tends to break along straight lines are crystalline solid.
A crystal/ crystalline solid is a solid material in which its constituents such as atoms, molecules and/or ions are arranged in an ordered microscopic structure which eventually forms into a crystal lattice that goes in all directions. Its atoms are strategically formed in a periodic arrangement known as the crystal structure. It is intrinsic in nature that repetitively forms symmetric patterns in a three-dimensional space matter.