system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do "normal" or "generic" bricks almost always have some sort of orange-red color and why do said colors sometimes become darker?
gpt
Bricks are made of clay from the Earth, and the specific clay they use has iron in it. When iron is exposed to oxygen, it turns red/orange (like rust).

Bricks become darker over time because they are porous (lots of little holes in them) that can be filled with dirt. Power-washing can bring them back to life :)