The randomly placed resources are described here https://forums.elementalgame.com/399857
In summary, you got the following resources on a map at start
1) Resources that each player gains when starting (in 1.09e that's a gold mine, a forgotten library and a fertile land)
2) Resources that are randomly placed (see topic above)
3) Resources that are placed due to talents that give additional resources
4) Resources that are placed due to technology that unlocks new resources)
5) Resources that are pre-placed on maps.
If you want a particular map to have more resources, your best option is to go with more of 5).