Idea is good with two drawbacks:
1. I really have no idea how to show in small icon that mod changes resource generation.
2. I have close to none graphical skills.
If someone would have an idea and propse a picture I'll be happy to add it.
How about this: Use the image that shows the max distance on the map that uses your mod, with visible resource patches. So people get an idea of what it does differently from vanilla.
