What If Slate Kept Grudges

What if slate, splitting so cleanly along its planes, wasn't releasing pressure but choosing a side. Every roof tile a decision made under heat nobody witnessed, sediment layered thin as opinion, then locked. Quarrymen call it cleavage like it's simple, like the rock just gives. But watch how it always breaks the same direction, never across, never against its own old argument. Something in there decided, once, which way to fail. Now every shard follows the ruling, generation after generation of chipped grey conviction. Buildings roofed in it are roofed in consensus. Rain hits, and slides off along lines drawn before the first hand ever touched stone.