I recently bought a 1-pound .999 fine copper bar. I was curious to know how closely the density of my bar was with the actual density of copper (about 8.96 g/cc). My bar measured 1 pound .5 oz (467.76 g). I calculated the volume two ways, water displacement and measurement; the volume is 48cc. Therefore the density is calculated as 9.745 g/cc (467.76/48). Why is my bar denser than the actual density of copper. It makes me think the bar isn't pure, but is mixed with another denser metal. Any thoughts?