There's a reason you don't put ore fields in home systems, it's so one faction does not have the monopoly over the fields. I do not understand the reasoning for putting the ore fields in Vespucci at all, it makes no sense. Legion does not get any mining bonus. You want to make it accessible to any miner, transport and pirate imo. No other faction in the game has ore fields in their home system..... this is very confusing.