Conversation so far:
When did the Etruscans expand?
Etruscan expansion into Southern Italy, present day Campania region, and northwards into the Po Valley occurred yet in the 9th century BC.
What was the outcome of Etruscan focus beyond the Apennine Mountains and into Campania?
Some small towns in the sixth century BC disappeared during this time, ostensibly subsumed by greater, more powerful neighbours.

Question: how did this mining proceed as they expanded?
Self-contained rewrite: How did mining proceed as Etruscans expanded?