Measurements of lead in the ice of Greenland’s glaciers, which show a staggering increase in concentration during this period, bear witness to the volumes of poisonous smoke they belched out.8 The ore being smelted was silver: it has been estimated that for every ton of silver extracted over ten thousand tons of rock had to be quarried. It has also been estimated that by the early first century BC, the Roman mint was using fifty tons of silver each year.
