metal

金属　—　Measuring

Matter that gives back light and spreads when it is struck.

Aureus of Augustus — A photograph of the real thing this term names.

Aureus of Claudius (found in Southern India) — A photograph of the real thing this term names.

⚠ Metal was chosen as the material for currency because it does not corrode, can be divided, and can be melted down and restored. The fact that it "can be restored" was key — even in failure, the material is not lost.