People moved around surprisingly often, whether for better prospects or better pay. Tin miners from Cornwall took up positions in all sorts of places. The coal mines of Burnley would be an easy move. Some went much further afield, mining metal ores in South America.
It was normal to end up somewhere where the skills you already had could be used.
So farm labourers might emigrate to places where they might have land of their own.
Miners could find work in any sort of mine - in Cumberland there were coal mines and iron ore mines, and people shifted between them. Tin miners were used to dealing with hard granite, and would be good prospects for any railway company that had a tunnel to construct.
Labourers could, of course, find work pretty much anywhere, whether in fields, in mines or on building sites.