… why is this so unknown?

you should do some more advertisement :P

This mod is fairly new. For the longest time I assumed that Ore Chaos does everything and I only wrote this mod as a no-download script for multiplayer.

I think there is another (older) mod that does something similar.

What I really think would be nice is a way to keep the vanilla ore patches intact and add this impure ore patches (with higher quantity that can be harvested before it depletes - is it called richness?).

So, for example, we could set the map to have fewer pure ore patches + lots of impure patches. OR have normal distribution, but pure patches being poor and impure patches richer... etc.

But I guess that isn't possible to implement without the devs intervention (engine limitation), right?

It's possible to do that. But the intent of the mod is to increase difficulty, not necessarily add more variety.

Then, can you make a separate mod for that?

I think such mod will gather a lot of interest.

i had seen another mod once that allowed to specify lots of details where to place how much ore of which type and how much ore in which type of ore field to replace with which other types of ore. that ended up in having two screenfull of mod settings which wasn't easy to handle to get good results, and thus i didn't use it.

this mod is really nice and easy to configure. let's keep it this way
(at least mostly, i always have ideas which additional/different mod settings i might like :-)