refill mines

I get a message when I log in "Refill your mines before they run empty"
Great --- HOW?

go to Gem shop or Trader
Deposit Tab-u can find various deposits u can use to refill. Buy them with gems and place on a deposit u want to refill
Finished

Remember that when paying gems to refill a mine you're saving the cost of the MINE not the cost of the refilled material. Basically, it's only worth refilling upgraded mines, and then only expensive ones.

Bobmcar is right- if you run highly upgraded iron mines or any gold mines they might be worth refilling depending upon you're production needs.