Because I am bored I thought I would try to further confuse you so that you get a feel for the scope of what your wanting to do:
It sounds like you want to make a game but you are asking about maps... this tells me that you are making a game and maps.
each unit in the game has it's own Lua-object-model which you would need to code in such a way as to handle the new resource... much of this could be included from a general new default unit.
You would need to have some kind of Lua code in the game (we often call these "gadgets" for synced code and "widgets" for unsynced code but it's all "game" code) to negotiation communication between these unit scripts, the graphical user interface you expect players to use to interact with the new resource coded of your units and the map or gaia units you are getting to handle resources.
In your map you would need code to communicated with the game code, units and user interface... though ideally this would just be a list of gold locations for the game to read etc.
That said... other people have created open source scripts that do a lot of this type of things for their own games... so once you figure out how to read Lua and game assets and understand how it all fit's together you'll be able to find a lot of what you need is already done.
Here are some starting points:
Like I said, you've described a game that uses custom maps so the first thing to figure out is how to make a game:http://springrts.com/wiki/Game_and_Unit ... evelopment
you should probably try to work through one of the tutorials like http://springrts.com/wiki/The_Complete_ ... pring_Game
will take you from 0 to having a model in game... (I wrote much of "Simple Game Tutorial" back before people had even started thinking about things like Lua and were still using 3do models so it is exceptionally out-dated...)
Once you get a basic handle on that you can dive into Spring Lua Scripting, Spring's Lua Interface is basically a bunch of hooks that attach to the engine that will take a while to get your head wrapped around... but Lua shouldn't be too hard to get a basic start on:http://springrts.com/wiki/Lua_Scripting
one idea would be to create a widget... widgets are unsynced code that can run in most games so you'd be able to get a feel for Spring Lua Scripting without having to wrap your head around making games and units and maps and hooking them all together.http://springrts.com/wiki/Lua_Widgets