No raw materials

[TheSaint2009]

So how does one upgrade the clay pit? My bricks are out???
Also iron rations are out?

[numbnutz]

depends if says unlimited supply possible or not. some are some arent upgradable to deep pit mining.

http://forum.sunflowers.de/showthread.php?t=12761

[LadyH]

It depends research at the shool also :go:

[MinGraphics]

Do all the research at the school and than click on the mine, if you can upgrade it there will be a green dot at the top of the information on that mine. It is just like the ones that appearer on the houses and the warehouses when you can upgrade them.