 Complete the following phrase:  By the 14th century, the majority of the more easily accessible ore deposits were exhausted. Thus, more advanced technological achievements were introduced in order to keep up with the demand in metal. The alchemical laboratory, separating precious metals from the baser ones they are typically found with, was an essential feature of the metallurgical enterprise. However, a significant hiatus in underground mining was noted during the 14th and the early 15th century because of a series of historical events with severe social and economic impacts. The 