Hey there @Mishka, welcome to the Discourse! First, I am going to page @Drotten, our Modding Support to see what information he can provide. Next, I would recommend that you review the Modding rule(s) here:
http://discourse.stonehearth.net/t/one-rule-to-ring-them-all/16926
After, the Stonehearth devs have a starter mod that might be of some help here: GitHub - stonehearth/startermod_basic: A most basic starter mod to get you going!.
And finally, you may be able to use this tutorial for more information:
Tutorial: Adding Mining Resources (updated for Alpha 18)
Good Luck!