Miners Won't Gather Basic Minerals?

It seems that no matter how many times I send out miners to mines displaying minerals but no rares, they come back empty-handed. One suggestion that was made was that the mines were in a "recharge" cycle, but I cannot believe that this is the case with as many times as I've tried to gather the basic minerals needed to build more miners. To limit the gathering of those basic minerals to only cotters seems totally illogical, as the rationalization would have to be that the job is too simple for the more advanced miners. Can anyone shed some light on this topic?

Edited by Abraxox - 15 Aug 2012 at 14:40

If this isn't an issue that is being addressed, then miners and herbalists are only of any use at sites with "rares," and since those are in limited supply, and many are "claimed," it is a guarantee to create in-game conflict, which would probably be the goal.

Cotters for hides, ordinary minerals, ordinary herbs, and (extra research) grapes.  Skinners for animal parts (NOT hides) and elemental salts.  Miners for rare minerals (NOT ordinary minerals).  Herbalists for rare herbs (NOT ordinary herbs, NOT grapes). 

Abraxox wrote: This implementation is obviously geared to benefit smaller players, then, and offers an impediment to large established cities. It must also be intended to create more conflict between players.

Technically, cotters are helpful for "developing" players as well. I have a total of 8 cities, 2 of which have almost nothing except for cottages. These cottages will be slowly replaced by buildings, leveling it up to 20 before demolishing the next cottage.