Copper is a chemical element with symbol Cu, and atomic number 29. It is a soft, malleable and ductile metal with very high thermal and electrical conductivity.
C 0146 (OTTO) Copper slug, 6.35mm (0.25in) dia x 6.35mm (0.25in) length, 99.9999% Cas 7440-50-8 - used in the concrete as one of the alternative materials.