Underwater mines producing brightstone—crystal formations that emit brilliant, permanent light. The mines are deep, dangerous, and entirely triton-controlled. Vetral sells brightstone sparingly, keeping prices astronomical.
The stones are fragile as glass and must be harvested delicately. Broken brightstone goes dark permanently. This has led to elaborate underwater mining techniques and a lucrative smuggling trade in "cracked bright"—damaged stones that still glow faintly.