The coarse copper could only be added to the fineries in small pieces. Their larger surface area aided the smelting process.
Smaller, thinner pieces were broken up cold using the pestle, while larger pieces first needed to be heated. To do this, they were placed on the copper breaking hearth. This was similar to a liquating hearth, but instead of crucibles, there were large iron plates set into the ground in front of the hearth, on which the copper could then be broken into pieces.