it is a bit unaccurrate

One test went for 5 minutes.
i was a bit lazy with stopping so in the graphs you must look at the 5minute mark, not the end.
i did not touch/controll the miners other then putting about 2 per rock at the start, no "microing" them.
all tests on eurekaV2 map in the flat areas.
first, 4 mex:
ie 3 starting mex+1 extra mex.
after 5 minutes: ~4000 m
very constant income of course, one mex does 3.1 (a bit over the "standard" of ~2.0 that most spring maps use i think)

6 miners with a little distance to travel

metal income of this test: ~2500m
so less metal income than the 4 mex but the distance is quite big and more miners could work there without clogging up, i think.
the income is quite constant too, over the time of a game it is almost linear. only small ditches when a rock was mined out or 2 workers blocked each other for a moment or whatever.

6 miners, closer to the rocks:
this might be about the usual distance if you do not move the depots nearer all the time and do not go too near to avoid clogging

metal income of these 6 close miners: ~4000
so about the same as 4 mex

if you look very close, mining slowed downed at one point. the power of paint makes this visible:

maybe happend when the near rock was mined out or maybe miners just went to further away rocks by stupidness, i didnt watch close enough. or just inaccurate test, pathing blabla
conclusion:
mining income is surprisingly close to mex even most values were guessed.
6 miners mining some rocks = 4 mex.
of course distance influences the result but is not yet clear how much. ie how the income in the "close" test would be without the closest rock.
In the testgames the income did not seem so far off either. Of course disregarding that the map got flooded in space rocks every 2 minutes

What could be changed is how much metal can be mined from a rock... could be a bit less, half or so.
next week:
how much wood would a woodchuck chuck if instead of miners mining mineable rocks there would be chuckable wood?
also +1 internet to whom finds the hidden bug to boost mining speed by ├╝bermicro