Then new layers of bruised pyrites were arranged so as to form an immense heap, the exterior of which was covered with earth and grass, several air-holes being left, as if it was a stack of wood which was to be carbonized to make charcoal.
Entonces se echaron nuevas capas de piritas machacadas, dispuestas de modo que formasen un montón grande, que fueron cubiertas de tierra y hierbas, dejando, sin embargo, alguna abertura para que entrara el aire, como si se tratara de carbonizar leña para hacer carbón.