I would say I forgot the quasi- and para-elementals in yesterday's post, but I really didn't. I've never felt those were as conceptually pure as the primary elementals and so not as rich for turning into whole planes. Do we really need a whole Plane of Ooze?
After thinking about it a bit, I do think there is a little bit to be said. I do like the idea of elemental mixing; I mean, that is the source of the Prime Material Plane, after all. I just don't think we need whole plans of them. Maybe they're just the phase boundaries between the elements? I suppose you could still call them "planes" if you wanted, but they would really be the overlap between planes.
In any case, I'm pretty sure this is what the area of Quasi-Elemental Mineral looks like:
I'm not convinced that currently list of para-elementals is complete either. It would seem to me that the more watery side of a water/earth mixing might be silt or sediment rather than ooze. The airy end of the air/water boundary would be mist (perhaps freezing mist) rather than ice.
Oh, and in case you were wondering about the Positive and Negative Planes that finish out the Inner Planes, check out this post from exactly 3 years ago.
43 minutes ago