The Mining Effort
The Miner in San Pasquale asks Scarlett to help him re-open the Copper Mine, first by eliminating all the Delvers that have infested the mine and then by finding him new workers who will work in the mine.
First, Scarlett will have to get rid of the Delvers that infest the mine. Since she was already in the copper mine looking for Moonstone, this means finishing exploring all the tunnels and eliminating the remaining Delvers. (She doesn't have to open the closed off area by the abandoned entrance to do that.) Talk to the Miner to complete the Delvers part of the quest and obtain the second part, getting new miners to work the mines.
Scarlett can only complete this quest once she gets to Venice. In the Skullbreak Tavern in the Arsenal District there are three workers, one of them is glad to talk to Scarlett about this opportunity and promises to go to San Pasquale.