[Tomgs]

Another reason that you find mineral mining planets on worlds that have low mineral percentages is that the catchall world type (the Last entry in each section) is a mining colony world. This means that any world that isn't used as any other type becomes a mining planet. If you change this I don't know what would happen you might be able to make it into a research or other type world instead but there has to be a catch all or there might be errors cropping up. Thats why there is a mining colony type at the end of each section that has a maximum of 100 worlds per system.