I would like to put forward the suggestion that production facilities that work with marble or stone (And i'm guessing granite as well) continue to mine the site there currently working on till its depleted rather than leave it and start to mine the fresh one or that you have the ability to select which site they are to work on if multiple are available. I ask this because of my low level i don't have many marble sites and because of the low amount thats in them they tend to be depleted or near depletion after one nights sleep and when i send out the geologist to find a new one and it pops up next to a almost depleted site the worker switches leaving that one with like 20-30 marble remaining and wont go back till he's depleted that new site.