Antimony
The gleaming, brittle silver of this flake of antimony is bright and clear, unmarked by rust or patina. Its paper-thin shape is crumpled slightly, giving it a reflective brilliance, and it reflects the available light in a rippling pattern.
Antimony flakes are alchemical minerals, which can be stored in the rift. Administered by eating, it reduces the fluid level in your body when artificially raised.