Complex sentence: The Romans had great need for lead, especially for the plumbing systems in their dwellings, and mined the ore galena extensively during their time in Britain, so it is possible that Odin Mine does have Roman origins.
Split into simpler sentences: The Romans had great need for lead, especially for the plumbing systems in their dwellings. They mined the ore galena extensively during their time in Britain, so it is possible that Odin Mine does have Roman origins.