Cu weight 8,96 g/cm3
100* 50* 1 is 5000 cm3
(8,96 * 5000 is 44800 G- 44.8 kg bar.
What have these bars being used for?
If it was mine i will grind of the gold with sandpaper, and recover the dust. It is easy with the shape of a bar, and if you use wet grinding paper you can control the wet dust with no loose of gold. Remember to recover the sandpaper.
Henrik